绋嬪簭12-14 linux/fs/exec.c

  1 /*

  2  *  linux/fs/exec.c

  3  *

  4  *  (C) 1991  Linus Torvalds

  5  */

  6

  7 /*

  8  * #!-checking implemented by tytso.

  9  */

    /*

     * #!寮�濮嬬殑鑴氭湰绋嬪簭鐨勬��娴嬩唬鐮侀儴鍒嗘槸鐢�tytso瀹炵幇鐨勩��

     */

 10

 11 /*

 12  * Demand-loading implemented 01.12.91 - no need to read anything but

 13  * the header into memory. The inode of the executable is put into

 14  * "current->executable", and page faults do the actual loading. Clean.

 15  *

 16  * Once more I can proudly say that linux stood up to being changed: it

 17  * was less than 2 hours work to get demand-loading completely implemented.

 18  */

    /*

     * 闇�姹傛椂鍔犺浇瀹炵幇浜�1991.12.1 - 鍙�闇�灏嗘墽琛屾枃浠跺ご閮ㄨ�昏繘鍐呭瓨鑰屾棤椤诲皢鏁翠釜

     * 鎵ц�屾枃浠堕兘鍔犺浇杩涘唴瀛樸�傛墽琛屾枃浠剁殑i鑺傜偣琚�鏀惧湪褰撳墠杩涚▼鐨勫彲鎵ц�屽瓧娈典腑

     * "current->executable"锛岄〉寮傚父浼氳繘琛屾墽琛屾枃浠剁殑瀹為檯鍔犺浇鎿嶄綔銆傝繖寰堝畬缇庛��

     *

     * 鎴戝彲浠ュ啀涓�娆¤嚜璞�鍦拌�达紝linux缁忓緱璧蜂慨鏀癸細鍙�鐢ㄤ簡涓嶅��2灏忔椂鐨勫伐浣滄椂闂村氨

     * 瀹屽叏瀹炵幇浜嗛渶姹傚姞杞藉�勭悊銆�

     */

 19

 20 #include <signal.h>       // 淇″彿澶存枃浠躲�傚畾涔変俊鍙风�﹀彿甯搁噺锛屼俊鍙风粨鏋勫強淇″彿鎿嶄綔鍑芥暟鍘熷瀷銆�

 21 #include <errno.h>        // 閿欒��鍙峰ご鏂囦欢銆傚寘鍚�绯荤粺涓�鍚勭�嶅嚭閿欏彿銆�

 22 #include <string.h>       // 瀛楃�︿覆澶存枃浠躲�備富瑕佸畾涔変簡涓�浜涙湁鍏冲瓧绗︿覆鎿嶄綔鐨勫祵鍏ュ嚱鏁般��

 23 #include <sys/stat.h>     // 鏂囦欢鐘舵�佸ご鏂囦欢銆傚惈鏈夋枃浠剁姸鎬佺粨鏋�stat{}鍜岀�﹀彿甯搁噺绛夈��

 24 #include <a.out.h>        // a.out澶存枃浠躲�傚畾涔変簡a.out鎵ц�屾枃浠舵牸寮忓拰涓�浜涘畯銆�

 25

 26 #include <linux/fs.h>     // 鏂囦欢绯荤粺澶存枃浠躲�傚畾涔夋枃浠惰〃缁撴瀯锛�file銆�m_inode锛夌瓑銆�

 27 #include <linux/sched.h>  // 璋冨害绋嬪簭澶存枃浠讹紝瀹氫箟浜嗕换鍔＄粨鏋�task_struct銆佷换鍔�0鏁版嵁绛夈��

 28 #include <linux/kernel.h> // 鍐呮牳澶存枃浠躲�傚惈鏈変竴浜涘唴鏍稿父鐢ㄥ嚱鏁扮殑鍘熷舰瀹氫箟銆�

 29 #include <linux/mm.h>     // 鍐呭瓨绠＄悊澶存枃浠躲�傚惈鏈夐〉闈㈠ぇ灏忓畾涔夊拰涓�浜涢〉闈㈤噴鏀惧嚱鏁板師鍨嬨��

 30 #include <asm/segment.h>  // 娈垫搷浣滃ご鏂囦欢銆傚畾涔変簡鏈夊叧娈靛瘎瀛樺櫒鎿嶄綔鐨勫祵鍏ュ紡姹囩紪鍑芥暟銆�

 31

 32 extern int sys_exit(int exit_code);     // 閫�鍑虹▼搴忕郴缁熻皟鐢ㄣ��

 33 extern int sys_close(int fd);           // 鍏抽棴鏂囦欢绯荤粺璋冪敤銆�

 34

 35 /*

 36  * MAX_ARG_PAGES defines the number of pages allocated for arguments

 37  * and envelope for the new program. 32 should suffice, this gives

 38  * a maximum env+arg of 128kB !

 39  */

    /*

     * MAX_ARG_PAGES瀹氫箟浜嗕负鏂扮▼搴忓垎閰嶇殑缁欏弬鏁板拰鐜�澧冨彉閲忎娇鐢ㄧ殑鏈�澶у唴瀛橀〉鏁般��

     * 32椤靛唴瀛樺簲璇ヨ冻澶熶簡锛岃繖浣垮緱鐜�澧冨拰鍙傛暟锛�env+arg锛夌┖闂寸殑鎬诲拰杈惧埌128kB!

     */

 

 40 #define MAX_ARG_PAGES 32

 41

    //// 浣跨敤搴撴枃浠剁郴缁熻皟鐢ㄣ��

    // 鍙傛暟锛�library - 搴撴枃浠跺悕銆�

    // 涓鸿繘绋嬮�夋嫨涓�涓�搴撴枃浠讹紝骞舵浛鎹㈣繘绋嬪綋鍓嶅簱鏂囦��i鑺傜偣瀛楁�靛�间负杩欓噷鎸囧畾搴撴枃浠跺悕鐨�i鑺傜偣

    // 鎸囬拡銆傚�傛��library鎸囬拡涓虹┖锛屽垯鎶婅繘绋嬪綋鍓嶇殑搴撴枃浠堕噴鏀炬帀銆�

    // 杩斿洖锛氭垚鍔熻繑鍥�0锛屽惁鍒欒繑鍥炲嚭閿欑爜銆�

 42 int sys_uselib(const char * library)

 43 {

 44         struct m_inode * inode;

 45         unsigned long base;

 46

    // 棣栧厛鍒ゆ柇褰撳墠杩涚▼鏄�鍚︽櫘閫氳繘绋嬨�傝繖鏄�閫氳繃鏌ョ湅褰撳墠杩涚▼鐨勭┖闂撮暱搴︽潵鍋氬埌鐨勩�傚洜涓烘櫘閫氳繘

    // 绋嬬殑绌洪棿闀垮害琚�璁剧疆涓�TASK_SIZE锛�64MB锛夈�傚洜姝よ嫢杩涚▼閫昏緫鍦板潃绌洪棿闀垮害涓嶇瓑浜�TASK_SIZE

    // 鍒欒繑鍥炲嚭閿欑爜锛堟棤鏁堝弬鏁帮級銆傚惁鍒欏彇搴撴枃浠�i鑺傜偣inode銆傝嫢搴撴枃浠跺悕鎸囬拡绌猴紝鍒欒�剧��inode

    // 绛変簬NULL銆�

 47         if (get_limit(0x17) != TASK_SIZE)

 48                 return -EINVAL;

 49         if (library) {

 50                 if (!(inode=namei(library)))            /* get library inode */

 51                         return -ENOENT;                 /* 鍙栧簱鏂囦欢i鑺傜偣 */

 52         } else

 53                 inode = NULL;

 54 /* we should check filetypes (headers etc), but we don't */

    /* 鎴戜滑搴旇�ユ��鏌ヤ竴涓嬫枃浠剁被鍨嬶紙濡傚ご閮ㄤ俊鎭�绛夛級锛屼絾鏄�鎴戜滑杩樻病鏈夎繖鏍峰仛銆� */

    // 鐒跺悗鏀惧洖杩涚▼鍘熷簱鏂囦欢i鑺傜偣锛屽苟棰勭疆杩涚▼搴�i鑺傜偣瀛楁�典负绌恒�傛帴鐫�鍙栧緱杩涚▼鐨勫簱浠ｇ爜鎵�鍦�

    // 浣嶇疆锛屽苟閲婃斁鍘熷簱浠ｇ爜鐨勯〉琛ㄥ拰鎵�鍗犵敤鐨勫唴瀛橀〉闈��傛渶鍚庤�╄繘绋嬪��i鑺傜偣瀛楁�垫寚鍚戞柊搴�i鑺�

    // 鐐癸紝骞惰繑鍥�0锛堟垚鍔燂級銆�

 55         iput(current->library);

 56         current->library = NULL;

 57         base = get_base(current->ldt[2]);

 58         base += LIBRARY_OFFSET;

 59         free_page_tables(base,LIBRARY_SIZE);

 60         current->library = inode;

 61         return 0;

 62 }

 63

 64 /*

 65  * create_tables() parses the env- and arg-strings in new user

 66  * memory and creates the pointer tables from them, and puts their

 67  * addresses on the "stack", returning the new stack pointer value.

 68  */

    /*

     * create_tables()鍑芥暟鍦ㄦ柊浠诲姟鍐呭瓨涓�瑙ｆ瀽鐜�澧冨彉閲忓拰鍙傛暟瀛楃�︿覆锛岀敱姝�

     * 鍒涘缓鎸囬拡琛�锛屽苟灏嗗畠浠�鐨勫湴鍧�鏀惧埌"鏍�"涓婏紝鐒跺悗杩斿洖鏂版爤鐨勬寚閽堝�笺��

     */

    //// 鍦ㄦ柊浠诲姟鏍堜腑鍒涘缓鍙傛暟鍜岀幆澧冨彉閲忔寚閽堣〃銆�

    // 鍙傛暟锛�p -鏁版嵁娈典腑鍙傛暟鍜岀幆澧冧俊鎭�鍋忕Щ鎸囬拡锛�argc - 鍙傛暟涓�鏁帮��envc - 鐜�澧冨彉閲忎釜鏁般��

    // 杩斿洖锛氭爤鎸囬拡鍊笺��

 69 static unsigned long * create_tables(char * p,int argc,int envc)

 70 {

 71         unsigned long *argv,*envp;

 72         unsigned long * sp;

 73

    // 鏍堟寚閽堟槸浠�4瀛楄妭锛�1鑺傦級涓鸿竟鐣岃繘琛屽�诲潃鐨勶紝鍥犳�よ繖閲岄渶璁� sp涓�4鐨勬暣鏁板�嶅�笺�傛�ゆ��sp

    // 浣嶄簬鍙傛暟鐜�澧冭〃鐨勬湯绔�銆傜劧鍚庢垜浠�鍏堟��sp 鍚戜笅锛堜綆鍦板潃鏂瑰悜锛夌Щ鍔�锛屽湪鏍堜腑绌哄嚭鐜�澧冨彉閲�

    // 鎸囬拡鍗犵敤鐨勭┖闂达紝骞惰�╃幆澧冨彉閲忔寚閽�envp 鎸囧悜璇ュ�勩�傚�氱┖鍑虹殑涓�涓�浣嶇疆鐢ㄤ簬鍦ㄦ渶鍚庡瓨鏀句竴

    // 涓�NULL鍊笺�備笅闈㈡寚閽堝姞1锛�sp灏嗛�掑�炴寚閽堝�藉害瀛楄妭鍊硷紙4瀛楄妭锛夈�傚啀鎶�sp鍚戜笅绉诲姩锛岀┖鍑�

    // 鍛戒护琛屽弬鏁版寚閽堝崰鐢ㄧ殑绌洪棿锛屽苟璁�argv 鎸囬拡鎸囧悜璇ュ�勩�傚悓鏍凤紝澶氱┖澶勭殑涓�涓�浣嶇疆鐢ㄤ簬瀛樻��

    // 涓�涓�NULL鍊笺�傛�ゆ��sp鎸囧悜鍙傛暟鎸囬拡鍧楃殑璧峰�嬪�勶紝鎴戜滑灏嗙幆澧冨弬鏁板潡鎸囬拡envp鍜屽懡浠よ�屽��

    // 鏁板潡鎸囬拡浠ュ強鍛戒护琛屽弬鏁颁釜鏁板�煎垎鍒�鍘嬪叆鏍堜腑銆�

 74         sp = (unsigned long *) (0xfffffffc & (unsigned long) p);

 75         sp -= envc+1;                              // 鍗�sp = sp - (envc+1);

 76         envp = sp;

 77         sp -= argc+1;

 78         argv = sp;

 79         put_fs_long((unsigned long)envp,--sp);

 80         put_fs_long((unsigned long)argv,--sp);

 81         put_fs_long((unsigned long)argc,--sp);

    // 鍐嶅皢鍛戒护琛屽悇鍙傛暟鎸囬拡鍜岀幆澧冨彉閲忓悇鎸囬拡鍒嗗埆鏀惧叆鍓嶉潰绌哄嚭鏉ョ殑鐩稿簲鍦版柟锛屾渶鍚庡垎鍒�鏀剧疆涓�

    // 涓�NULL鎸囬拡銆�

 82         while (argc-->0) {

 83                 put_fs_long((unsigned long) p,argv++);

 84                 while (get_fs_byte(p++)) /* nothing */ ; // p鎸囬拡鎸囧悜涓嬩竴涓�鍙傛暟涓层��

 85         }

 86         put_fs_long(0,argv);

 87         while (envc-->0) {

 88                 put_fs_long((unsigned long) p,envp++);

 89                 while (get_fs_byte(p++)) /* nothing */ ; // p鎸囬拡鎸囧悜涓嬩竴涓�鍙傛暟涓层��

 90         }

 91         put_fs_long(0,envp);

 92         return sp;                         // 杩斿洖鏋勯�犵殑褰撳墠鏂版爤鎸囬拡銆�

 93 }

 94

 95 /*

 96  * count() counts the number of arguments/envelopes

 97  */

    /*

     * count()鍑芥暟璁＄畻鍛戒护琛屽弬鏁�/鐜�澧冨彉閲忕殑涓�鏁般��

     */

    //// 璁＄畻鍙傛暟涓�鏁般��

    // 鍙傛暟锛�argv - 鍙傛暟鎸囬拡鏁扮粍锛屾渶鍚庝竴涓�鎸囬拡椤规��NULL銆�

    // 缁熻�″弬鏁版寚閽堟暟缁勪腑鎸囬拡鐨勪釜鏁般�傚叧浜庡嚱鏁板弬鏁颁紶閫掓寚閽堢殑鎸囬拡鐨勪綔鐢�锛岃�峰弬瑙佺▼搴�

    // kernel/sched.c涓�绗�171琛屽墠鐨勬敞閲娿��

    // 杩斿洖锛氬弬鏁颁釜鏁般��

 98 static int count(char ** argv)

 99 {

100         int i=0;

101         char ** tmp;

102

103         if (tmp = argv)

104                 while (get_fs_long((unsigned long *) (tmp++)))

105                         i++;

106

107         return i;

108 }

109

110 /*

111  * 'copy_string()' copies argument/envelope strings from user

112  * memory to free pages in kernel mem. These are in a format ready

113  * to be put directly into the top of new user memory.

114  *

115  * Modified by TYT, 11/24/91 to add the from_kmem argument, which specifies

116  * whether the string and the string array are from user or kernel segments:

117  *

118  * from_kmem     argv *        argv **

119  *    0          user space    user space

120  *    1          kernel space  user space

121  *    2          kernel space  kernel space

122  *

123  * We do this by playing games with the fs segment register.  Since it

124  * it is expensive to load a segment register, we try to avoid calling

125  * set_fs() unless we absolutely have to.

126  */

    /*

     * 'copy_string()'鍑芥暟浠庣敤鎴峰唴瀛樼┖闂存嫹璐濆弬鏁�/鐜�澧冨瓧绗︿覆鍒板唴鏍哥┖闂查〉闈�涓�銆�

     * 杩欎簺宸插叿鏈夌洿鎺ユ斁鍒版柊鐢ㄦ埛鍐呭瓨涓�鐨勬牸寮忋��

     *

     * 鐢�TYT(Tytso)浜�1991.11.24鏃ヤ慨鏀癸紝澧炲姞浜�from_kmem鍙傛暟锛岃�ュ弬鏁版寚鏄庝��

     * 瀛楃�︿覆鎴栧瓧绗︿覆鏁扮粍鏄�鏉ヨ嚜鐢ㄦ埛娈佃繕鏄�鍐呮牳娈点��

     *

     * from_kmem   鎸囬拡argv *    瀛楃�︿�� argv **

     *    0         鐢ㄦ埛绌洪棿      鐢ㄦ埛绌洪棿

     *    1         鍐呮牳绌洪棿      鐢ㄦ埛绌洪棿

     *    2         鍐呮牳绌洪棿      鍐呮牳绌洪棿

     *

     * 鎴戜滑鏄�閫氳繃宸у�欏�勭悊fs娈靛瘎瀛樺櫒鏉ユ搷浣滅殑銆傜敱浜庡姞杞戒竴涓�娈靛瘎瀛樺櫒浠ｄ环澶�楂橈紝

     * 鎵�浠ユ垜浠�灏介噺閬垮厤璋冪��set_fs()锛岄櫎闈炲疄鍦ㄥ繀瑕併��

     */

    //// 澶嶅埗鎸囧畾涓�鏁扮殑鍙傛暟瀛楃�︿覆鍒板弬鏁板拰鐜�澧冪┖闂翠腑銆�

    // 鍙傛暟锛�argc - 娆叉坊鍔犵殑鍙傛暟涓�鏁帮��argv - 鍙傛暟鎸囬拡鏁扮粍锛�page - 鍙傛暟鍜岀幆澧冪┖闂撮〉闈㈡寚閽�

    // 鏁扮粍銆�p -鍙傛暟琛ㄧ┖闂翠腑鍋忕Щ鎸囬拡锛屽�嬬粓鎸囧悜宸插�嶅埗涓茬殑澶撮儴锛�from_kmem -瀛楃�︿覆鏉ユ簮鏍囧織銆�

    // 鍦� do_execve()鍑芥暟涓�锛�p鍒濆�嬪寲涓烘寚鍚戝弬鏁拌��(128kB)绌洪棿鐨勬渶鍚庝竴涓�闀垮瓧澶勶紝鍙傛暟瀛楃�︿覆

    // 鏄�浠ュ爢鏍堟搷浣滄柟寮忛�嗗悜寰�鍏朵腑澶嶅埗瀛樻斁鐨勩�傚洜姝� p鎸囬拡浼氶殢鐫�澶嶅埗淇℃伅鐨勫�炲姞鑰岄�愭笎鍑忓皬锛�

    // 骞跺�嬬粓鎸囧悜鍙傛暟瀛楃�︿覆鐨勫ご閮ㄣ�傚瓧绗︿覆鏉ユ簮鏍囧織from_kmem搴旇�ユ��TYT涓轰簡缁�execve()澧炴坊

    // 鎵ц�岃剼鏈�鏂囦欢鐨勫姛鑳借�屾柊鍔犵殑鍙傛暟銆傚綋娌℃湁杩愯�岃剼鏈�鏂囦欢鐨勫姛鑳芥椂锛屾墍鏈夊弬鏁板瓧绗︿覆閮藉湪鐢�

    // 鎴锋暟鎹�绌洪棿涓�銆�

    // 杩斿洖锛氬弬鏁板拰鐜�澧冪┖闂村綋鍓嶅ご閮ㄦ寚閽堛�傝嫢鍑洪敊鍒欒繑鍥�0銆�

127 static unsigned long copy_strings(int argc,char ** argv,unsigned long *page,

128                 unsigned long p, int from_kmem)

129 {

130         char *tmp, *pag;

131         int len, offset = 0;

132         unsigned long old_fs, new_fs;

133

    // 棣栧厛鍙栧綋鍓嶆�靛瘎瀛樺��ds锛堟寚鍚戝唴鏍告暟鎹�娈碉級鍜�fs鍊硷紝鍒嗗埆淇濆瓨鍒板彉閲�new_fs鍜�old_fs涓�銆�

    // 濡傛灉瀛楃�︿覆鍜屽瓧绗︿覆鏁扮粍锛堟寚閽堬級鏉ヨ嚜鍐呮牳绌洪棿锛屽垯璁剧��fs娈靛瘎瀛樺櫒鎸囧悜鍐呮牳鏁版嵁娈点��

134         if (!p)

135                 return 0;       /* bullet-proofing */  /* 鍋忕Щ鎸囬拡楠岃瘉 */

136         new_fs = get_ds();

137         old_fs = get_fs();

138         if (from_kmem==2)           // 鑻ヤ覆鍙婂叾鎸囬拡鍦ㄥ唴鏍哥┖闂村垯璁剧疆fs鎸囧悜鍐呮牳绌洪棿銆�

139                 set_fs(new_fs);

    // 鐒跺悗寰�鐜�澶勭悊鍚勪釜鍙傛暟锛屼粠鏈�鍚庝竴涓�鍙傛暟閫嗗悜寮�濮嬪�嶅埗锛屽�嶅埗鍒版寚瀹氬亸绉诲湴鍧�澶勩�傚湪寰�鐜�涓�锛�

    // 棣栧厛鍙栭渶瑕佸�嶅埗鐨勫綋鍓嶅瓧绗︿覆鎸囬拡銆傚�傛灉瀛楃�︿覆鍦ㄧ敤鎴风┖闂磋�屽瓧绗︿覆鏁扮粍锛堝瓧绗︿覆鎸囬拡锛夊湪

    // 鍐呮牳绌洪棿锛屽垯璁剧疆fs娈靛瘎瀛樺櫒鎸囧悜鍐呮牳鏁版嵁娈碉紙ds锛夈�傚苟鍦ㄥ唴鏍告暟鎹�绌洪棿涓�鍙栦簡瀛楃�︿覆鎸囬��

    // tmp涔嬪悗灏辩珛鍒绘仮澶�fs娈靛瘎瀛樺櫒鍘熷�硷紙fs鍐嶆寚鍥炵敤鎴风┖闂达級銆傚惁鍒欎笉鐢ㄤ慨鏀�fs鍊艰�岀洿鎺ヤ粠

    // 鐢ㄦ埛绌洪棿鍙栧瓧绗︿覆鎸囬拡鍒�tmp銆�

140         while (argc-- > 0) {

141                 if (from_kmem == 1)      // 鑻ヤ覆鎸囬拡鍦ㄥ唴鏍哥┖闂达紝鍒�fs鎸囧悜鍐呮牳绌洪棿銆�

142                         set_fs(new_fs);

143                 if (!(tmp = (char *)get_fs_long(((unsigned long *)argv)+argc)))

144                         panic("argc is wrong");

145                 if (from_kmem == 1)      // 鑻ヤ覆鎸囬拡鍦ㄥ唴鏍哥┖闂达紝鍒�fs鎸囧洖鐢ㄦ埛绌洪棿銆�

146                         set_fs(old_fs);

    // 鐒跺悗浠庣敤鎴风┖闂村彇璇ュ瓧绗︿覆锛屽苟璁＄畻璇ュ弬鏁板瓧绗︿覆闀垮害len銆� 姝ゅ悗tmp鎸囧悜璇ュ瓧绗︿覆鏈�绔�銆�

    // 濡傛灉璇ュ瓧绗︿覆闀垮害瓒呰繃姝ゆ椂鍙傛暟鍜岀幆澧冪┖闂翠腑杩樺墿浣欑殑绌洪棽闀垮害锛屽垯绌洪棿涓嶅�熶簡銆備簬鏄�鎭㈠��

    // fs娈靛瘎瀛樺櫒鍊硷紙濡傛灉琚�鏀瑰彉鐨勮瘽锛夊苟杩斿��0銆備笉杩囧洜涓哄弬鏁板拰鐜�澧冪┖闂寸暀鏈�128KB锛屾墍浠ラ��

    // 甯镐笉鍙�鑳藉彂鐢熻繖绉嶆儏鍐点��

147                 len=0;                         /* remember zero-padding */

148                 do {                           /* 鎴戜滑鐭ラ亾涓叉槸浠�NULL瀛楄妭缁撳熬鐨� */

149                         len++;

150                 } while (get_fs_byte(tmp++));

151                 if (p-len < 0) {               /* this shouldn't happen - 128kB */

152                         set_fs(old_fs);        /* 涓嶄細鍙戠敓-鍥犱负鏈�128kB鐨勭┖闂� */

153                         return 0;

154                 }

    // 鎺ョ潃鎴戜滑閫嗗悜閫愪釜瀛楃�﹀湴鎶婂瓧绗︿覆澶嶅埗鍒板弬鏁板拰鐜�澧冪┖闂存湯绔�澶勩�傚湪寰�鐜�澶嶅埗瀛楃�︿覆鐨勫瓧绗�

    // 杩囩▼涓�锛屾垜浠�棣栧厛瑕佸垽鏂�鍙傛暟鍜岀幆澧冪┖闂翠腑鐩稿簲浣嶇疆澶勬槸鍚﹀凡缁忔湁鍐呭瓨椤甸潃�傚�傛灉杩樻病鏈夊��

    // 鍏堜负鍏剁敵璇�1椤靛唴瀛橀〉闈��傚亸绉婚噺offset琚�鐢ㄤ綔涓哄湪涓�涓�椤甸潰涓�鐨勫綋鍓嶆寚閽堝亸绉诲�笺�� 鍥犱负

    // 鍒氬紑濮嬫墽琛屾湰鍑芥暟鏃讹紝鍋忕Щ鍙橀噺offset琚�鍒濆�嬪寲涓�0锛屾墍浠�(offset-1 < 0)鑲�瀹氭垚绔嬭�屼娇寰�

    // offset閲嶆柊琚�璁剧疆涓哄綋鍓�p鎸囬拡鍦ㄩ〉闈㈣寖鍥村唴鐨勫亸绉诲�笺��

155                 while (len) {

156                         --p; --tmp; --len;

157                         if (--offset < 0) {

158                                 offset = p % PAGE_SIZE;

159                                 if (from_kmem==2) // 鑻ヤ覆鍦ㄥ唴鏍哥┖闂村垯fs鎸囧洖鐢ㄦ埛绌洪棿銆�

160                                         set_fs(old_fs);

    // 濡傛灉褰撳墠鍋忕Щ鍊�p鎵�鍦ㄧ殑涓茬┖闂撮〉闈㈡寚閽堟暟缁勯」 page[p/PAGE_SIZE] ==0锛岃〃绀烘�ゆ��p鎸囬拡

    // 鎵�澶勭殑绌洪棿鍐呭瓨椤甸潰杩樹笉瀛樺湪锛屽垯闇�鐢宠�蜂竴绌洪棽鍐呭瓨椤碉紝骞跺皢璇ラ〉闈㈡寚閽堝～鍏ユ寚閽堟暟缁勶紝鍚�

    // 鏃朵篃浣块〉闈㈡寚閽�pag鎸囧悜璇ユ柊椤甸潰銆傝嫢鐢宠�蜂笉鍒扮┖闂查〉闈㈠垯杩斿��0銆�

161                                 if (!(pag = (char *) page[p/PAGE_SIZE]) &&

162                                     !(pag = (char *) page[p/PAGE_SIZE] =

163                                       (unsigned long *) get_free_page()))

164                                         return 0;

165                                 if (from_kmem==2) // 鑻ヤ覆鍦ㄥ唴鏍哥┖闂村垯fs鎸囧悜鍐呮牳绌洪棿銆�

166                                         set_fs(new_fs);

167

168                         }

    // 鐒跺悗浠�fs娈典腑澶嶅埗瀛楃�︿覆鐨�1瀛楄妭鍒板弬鏁板拰鐜�澧冪┖闂村唴瀛橀〉闈�pag鐨�offset澶勩��

169                         *(pag + offset) = get_fs_byte(tmp);

170                 }

171         }

    // 濡傛灉瀛楃�︿覆鍜屽瓧绗︿覆鏁扮粍鍦ㄥ唴鏍哥┖闂达紝鍒欐仮澶�fs娈靛瘎瀛樺櫒鍘熷�笺�傛渶鍚庯紝杩斿洖鍙傛暟鍜岀幆澧冪┖

    // 闂翠腑宸插�嶅埗鍙傛暟鐨勫ご閮ㄥ亸绉诲�笺��

172         if (from_kmem==2)

173                 set_fs(old_fs);

174         return p;

175 }

176

    //// 淇�鏀逛换鍔＄殑灞�閮ㄦ弿杩扮�﹁〃鍐呭�广��

    // 淇�鏀瑰眬閮ㄦ弿杩扮�﹁��LDT涓�鎻忚堪绗︾殑娈靛熀鍧�鍜屾�甸檺闀匡紝骞跺皢鍙傛暟鍜岀幆澧冪┖闂撮〉闈㈡斁缃�鍦ㄦ暟鎹�娈�

    // 鏈�绔�銆�

    // 鍙傛暟锛�text_size - 鎵ц�屾枃浠跺ご閮ㄤ��a_text瀛楁�电粰鍑虹殑浠ｇ爜娈甸暱搴﹀�硷紱

    // page - 鍙傛暟鍜岀幆澧冪┖闂撮〉闈㈡寚閽堟暟缁勩��

    // 杩斿洖锛氭暟鎹�娈甸檺闀垮�硷紙64MB锛夈��

177 static unsigned long change_ldt(unsigned long text_size,unsigned long * page)

178 {

179         unsigned long code_limit,data_limit,code_base,data_base;

180         int i;

181

    // 棣栧厛鎶婁唬鐮佸拰鏁版嵁娈甸暱搴﹀潎璁剧疆涓�64MB銆� 鐒跺悗鍙栧綋鍓嶈繘绋嬪眬閮ㄦ弿杩扮�﹁〃浠ｇ爜娈垫弿杩扮�︿腑浠�

    // 鐮佹�靛熀鍧�銆備唬鐮佹�靛熀鍧�涓庢暟鎹�娈靛熀鍧�鐩稿悓銆傚啀浣跨敤杩欎簺鏂板�奸噸鏂拌�剧疆灞�閮ㄨ〃涓�浠ｇ爜娈靛拰鏁版��

    // 娈垫弿杩扮�︿腑鐨勫熀鍧�鍜屾�甸檺闀裤�傝繖閲岃�锋敞鎰忥紝鐢变簬琚�鍔犺浇鐨勬柊绋嬪簭鐨勪唬鐮佸拰鏁版嵁娈靛熀鍧�涓庡師绋�

    // 搴忕殑鐩稿悓锛屽洜姝ゆ病鏈夊繀瑕佸啀閲嶅�嶅幓璁剧疆瀹冧滑锛屽嵆绗�186鍜�188琛屼笂鐨勪袱鏉¤�剧疆娈靛熀鍧�鐨勮��鍙�

    // 澶氫綑锛屽彲鐪佺暐銆�

182         code_limit = TASK_SIZE;

183         data_limit = TASK_SIZE;

184         code_base = get_base(current->ldt[1]);  // include/linux/sched.h锛岀��226琛屻��

185         data_base = code_base;

186         set_base(current->ldt[1],code_base);

187         set_limit(current->ldt[1],code_limit);

188         set_base(current->ldt[2],data_base);

189         set_limit(current->ldt[2],data_limit);

190 /* make sure fs points to the NEW data segment */

    /* 瑕佺‘淇�fs娈靛瘎瀛樺櫒宸叉寚鍚戞柊鐨勬暟鎹�娈� */

    // fs娈靛瘎瀛樺櫒涓�鏀惧叆灞�閮ㄨ〃鏁版嵁娈垫弿杩扮�︾殑閫夋嫨绗�(0x17)銆傚嵆榛樿�ゆ儏鍐典��fs閮芥寚鍚戜换鍔℃暟鎹�娈点��

191         __asm__("pushl $0x17\n\tpop %%fs"::);

    // 鐒跺悗灏嗗弬鏁板拰鐜�澧冪┖闂村凡瀛樻斁鏁版嵁鐨勯〉闈�锛堟渶澶氭湁MAX_ARG_PAGES椤碉紝128kB锛夋斁鍒版暟鎹�娈垫��

    // 绔�銆� 鏂规硶鏄�浠庤繘绋嬬┖闂村簱浠ｇ爜浣嶇疆寮�濮嬪�勯�嗗悜涓�椤典竴椤靛湴鏀俱�傚簱鏂囦欢浠ｇ爜鍗犵敤杩涚▼绌洪棿鏈�鍚�

    // 4MB銆傚嚱鏁�put_dirty_page()鐢ㄤ簬鎶婄墿鐞嗛〉闈㈡槧灏勫埌杩涚▼閫昏緫绌洪棿涓�銆傚湪mm/memory.c涓�銆�

192         data_base += data_limit - LIBRARY_SIZE;

193         for (i=MAX_ARG_PAGES-1 ; i>=0 ; i--) {

194                 data_base -= PAGE_SIZE;

195                 if (page[i])                           // 鑻ヨ�ラ〉闈㈠瓨鍦�锛屽氨鏀剧疆璇ラ〉闈���

196                         put_dirty_page(page[i],data_base);

197         }

198         return data_limit;                             // 鏈�鍚庤繑鍥炴暟鎹�娈甸檺闀匡��64MB锛夈��

199 }

200

201 /*

202  * 'do_execve()' executes a new program.

203  *

204  * NOTE! We leave 4MB free at the top of the data-area for a loadable

205  * library.

206  */

    /*

     * 'do_execve()'鍑芥暟鎵ц�屼竴涓�鏂扮▼搴忋��

     */

    //// execve()绯荤粺涓�鏂�璋冪敤鍑芥暟銆傚姞杞藉苟鎵ц�屽瓙杩涚▼锛堝叾浠栫▼搴忥級銆�

    // 璇ュ嚱鏁版槸绯荤粺涓�鏂�璋冪敤锛�int 0x80锛夊姛鑳藉彿__NR_execve璋冪敤鐨勫嚱鏁般�傚嚱鏁扮殑鍙傛暟鏄�杩涘叆绯荤��

    // 璋冪敤澶勭悊杩囩▼鍚庣洿鍒拌皟鐢ㄦ湰绯荤粺璋冪敤澶勭悊杩囩▼锛�system_call.s绗�200琛岋級鍜岃皟鐢ㄦ湰鍑芥暟涔嬪墠

    // 锛�system_call.s锛岀��203琛岋級閫愭�ュ帇鍏ユ爤涓�鐨勫�笺�傝繖浜涘�煎寘鎷�锛�

    // 鈶� 绗�86--88琛屽叆鍫嗙殑edx銆�ecx鍜�ebx瀵勫瓨鍣ㄥ�硷紝鍒嗗埆瀵瑰簲**envp銆�**argv鍜�*filename锛�

    // 鈶� 绗�94琛岃皟鐢�sys_call_table涓�sys_execve鍑芥暟锛堟寚閽堬級鏃跺帇鍏ユ爤鐨勫嚱鏁拌繑鍥炲湴鍧�锛�tmp锛夛紱

    // 鈶� 绗�202琛屽湪璋冪敤鏈�鍑芥��do_execve鍓嶅叆鏍堢殑鎸囧悜鏍堜腑璋冪敤绯荤粺涓�鏂�鐨勭▼搴忎唬鐮佹寚閽�eip銆�

    // 鍙傛暟锛�

    // eip - 璋冪敤绯荤粺涓�鏂�鐨勭▼搴忎唬鐮佹寚閽堬紝鍙傝��kernel/system_call.s绋嬪簭寮�濮嬮儴鍒嗙殑璇存槑锛�

    // tmp - 绯荤粺涓�鏂�涓�鍦ㄨ皟鐢�_sys_execve鏃剁殑杩斿洖鍦板潃锛屾棤鐢�锛�

    // filename - 琚�鎵ц�岀▼搴忔枃浠跺悕鎸囬拡锛�

    // argv - 鍛戒护琛屽弬鏁版寚閽堟暟缁勭殑鎸囬拡锛�

    // envp - 鐜�澧冨彉閲忔寚閽堟暟缁勭殑鎸囬拡銆�

    // 杩斿洖锛氬�傛灉璋冪敤鎴愬姛锛屽垯涓嶈繑鍥烇紱鍚﹀垯璁剧疆鍑洪敊鍙凤紝骞惰繑鍥�-1銆�

207 int do_execve(unsigned long * eip,long tmp,char * filename,

208         char ** argv, char ** envp)

209 {

210         struct m_inode * inode;

211         struct buffer_head * bh;

212         struct exec ex;

213         unsigned long page[MAX_ARG_PAGES];         // 鍙傛暟鍜岀幆澧冧覆绌洪棿椤甸潰鎸囬拡鏁扮粍銆�

214         int i,argc,envc;

215         int e_uid, e_gid;                          // 鏈夋晥鐢ㄦ埛ID鍜屾湁鏁堢粍ID銆�

216         int retval;

217         int sh_bang = 0;                           // 鎺у埗鏄�鍚﹂渶瑕佹墽琛岃剼鏈�绋嬪簭銆�

218         unsigned long p=PAGE_SIZE*MAX_ARG_PAGES-4; // p鎸囧悜鍙傛暟鍜岀幆澧冪┖闂寸殑鏈�鍚庨儴銆�

219

    // 鍦ㄦ�ｅ紡璁剧疆鎵ц�屾枃浠剁殑杩愯�岀幆澧冧箣鍓嶏紝璁╂垜浠�鍏堝共浜涙潅浜嬨�傚唴鏍稿噯澶囦簡128KB锛�32涓�椤甸潰锛�

    // 绌洪棿鏉ュ瓨鏀惧寲鎵ц�屾枃浠剁殑鍛戒护琛屽弬鏁板拰鐜�澧冨瓧绗︿覆銆備笂琛屾妸p鍒濆�嬭�剧疆鎴愪綅浜�128KB绌洪棿鐨�

    // 鏈�鍚�1涓�闀垮瓧澶勩�傚湪鍒濆�嬪弬鏁板拰鐜�澧冪┖闂寸殑鎿嶄綔杩囩▼涓�锛�p灏嗙敤鏉ユ寚鏄庡湪128KB绌洪棿涓�鐨勫��

    // 鍓嶄綅缃�銆�

    // 鍙﹀�栵紝鍙傛��eip[1]鏄�璋冪敤鏈�娆＄郴缁熻皟鐢ㄧ殑鍘熺敤鎴风▼搴忎唬鐮佹�靛瘎瀛樺��CS鍊硷紝鍏朵腑鐨勬�甸�夋嫨绗�

    // 褰撶劧蹇呴』鏄�褰撳墠浠诲姟鐨勪唬鐮佹�甸�夋嫨绗︼紙0x000f锛夈�傝嫢涓嶆槸璇ュ�硷紝閭ｄ箞 CS鍙�鑳戒細鏄�鍐呮牳浠ｇ爜

    // 娈电殑閫夋嫨绗� 0x0008銆� 浣嗚繖鏄�缁濆�逛笉鍏佽�哥殑锛屽洜涓哄唴鏍镐唬鐮佹槸甯搁┗鍐呭瓨鑰屼笉鑳借��鏇挎崲鎺夌殑銆�

    // 鍥犳�や笅闈㈡牴鎹�eip[1] 鐨勫�肩‘璁ゆ槸鍚︾�﹀悎姝ｅ父鎯呭喌銆傜劧鍚庡啀鍒濆�嬪��128KB鐨勫弬鏁板拰鐜�澧冧覆绌�

    // 闂达紝鎶婃墍鏈夊瓧鑺傛竻闆讹紝骞跺彇鍑烘墽琛屾枃浠剁殑i鑺傜偣銆傚啀鏍规嵁鍑芥暟鍙傛暟鍒嗗埆璁＄畻鍑哄懡浠よ�屽弬鏁板��

    // 鐜�澧冨瓧绗︿覆鐨勪釜鏁�argc鍜�envc銆傚彟澶栵紝鎵ц�屾枃浠跺繀椤绘槸甯歌�勬枃浠躲��

220         if ((0xffff & eip[1]) != 0x000f)

221                 panic("execve called from supervisor mode");

222         for (i=0 ; i<MAX_ARG_PAGES ; i++)       /* clear page-table */

223                 page[i]=0;

224         if (!(inode=namei(filename)))           /* get executables inode */

225                 return -ENOENT;

226         argc = count(argv);                     // 鍛戒护琛屽弬鏁颁釜鏁般��

227         envc = count(envp);                     // 鐜�澧冨瓧绗︿覆鍙橀噺涓�鏁般��

228        

229 restart_interp:

230         if (!S_ISREG(inode->i_mode)) {    /* must be regular file */

231                 retval = -EACCES;

232                 goto exec_error2;        //鑻ヤ笉鏄�甯歌�勬枃浠跺垯缃�鍑洪敊鐮侊紝璺宠浆鍒�376琛屻��

233         }

    // 涓嬮潰妫�鏌ュ綋鍓嶈繘绋嬫槸鍚︽湁鏉冭繍琛屾寚瀹氱殑鎵ц�屾枃浠躲�傚嵆鏍规嵁鎵ц�屾枃浠�i鑺傜偣涓�鐨勫睘鎬э紝鐪嬬湅鏈�

    // 杩涚▼鏄�鍚︽湁鏉冩墽琛屽畠銆傚湪鎶婃墽琛屾枃浠�i鑺傜偣鐨勫睘鎬у瓧娈靛�煎彇鍒�i涓�鍚庯紝鎴戜滑棣栧厛鏌ョ湅灞炴�т腑

    // 鏄�鍚﹁�剧疆浜嗏�滆�剧��-鐢ㄦ埛-ID鈥濓紙set-user_id锛夋爣蹇� 鍜屸�滆�剧��-缁�-ID鈥濓紙set-group-id锛夋爣

    // 蹇椼�傝繖涓や釜鏍囧織涓昏�佹槸璁╀竴鑸�鐢ㄦ埛鑳藉�熸墽琛岀壒鏉冪敤鎴凤紙濡傝秴绾х敤鎴�root锛夌殑绋嬪簭锛屼緥濡傛敼鍙�

    // 瀵嗙爜鐨勭▼搴�passwd绛夈�傚�傛��set-user-id鏍囧織缃�浣嶏紝鍒欏悗闈㈡墽琛岃繘绋嬬殑鏈夋晥鐢ㄦ��ID锛�euid锛�

    // 灏辫�剧疆鎴愭墽琛屾枃浠剁殑鐢ㄦ��ID锛屽惁鍒欒�剧疆鎴愬綋鍓嶈繘绋嬬��euid銆傚�傛灉鎵ц�屾枃浠�set-group-id琚�

    // 缃�浣嶇殑璇濓紝鍒欐墽琛岃繘绋嬬殑鏈夋晥缁�ID锛�egid锛夊氨璁剧疆涓烘墽琛屾枃浠剁殑缁�ID銆傚惁鍒欒�剧疆鎴愬綋鍓嶈繘绋�

    // 鐨�egid銆傝繖閲屾殏鏃舵妸杩欎袱涓�鍒ゆ柇鍑烘潵鐨勫�间繚瀛樺湪鍙橀噺e_uid鍜�e_gid涓�銆�

234         i = inode->i_mode;

235         e_uid = (i & S_ISUID) ? inode->i_uid : current->euid;

236         e_gid = (i & S_ISGID) ? inode->i_gid : current->egid;

 

    // 鐜板湪鏍规嵁杩涚▼鐨�euid鍜�egid鍜屾墽琛屾枃浠剁殑璁块棶灞炴�ц繘琛屾瘮杈冦�傚�傛灉鎵ц�屾枃浠跺睘浜庤繍琛岃繘绋�

    // 鐨勭敤鎴凤紝鍒欐妸鏂囦欢灞炴�у��i鍙崇Щ6浣嶏紝姝ゆ椂鍏舵渶浣�3浣嶆槸鏂囦欢瀹夸富鐨勮�块棶鏉冮檺鏍囧織銆傚惁鍒欑殑

    // 璇濆�傛灉鎵ц�屾枃浠朵笌褰撳墠杩涚▼鐨勭敤鎴峰睘浜庡悓缁勶紝鍒欎娇灞炴�у�兼渶浣�3浣嶆槸鎵ц�屾枃浠剁粍鐢ㄦ埛鐨勮�块棶

    // 鏉冮檺鏍囧織銆傚惁鍒欐�ゆ椂灞炴�у瓧鏈�浣�3浣嶅氨鏄�鍏朵粬鐢ㄦ埛璁块棶璇ユ墽琛屾枃浠剁殑鏉冮檺銆�

    // 鐒跺悗鎴戜滑鏍规嵁灞炴�у瓧i鐨勬渶浣�3姣旂壒鍊兼潵鍒ゆ柇褰撳墠杩涚▼鏄�鍚︽湁鏉冮檺杩愯�岃繖涓�鎵ц�屾枃浠躲�傚�傛��

    // 閫夊嚭鐨勭浉搴旂敤鎴锋病鏈夎繍琛屾敼鏂囦欢鐨勬潈鍔涳紙浣�0鏄�鎵ц�屾潈闄愶級锛屽苟涓斿叾浠栫敤鎴蜂篃娌℃湁浠讳綍鏉冮檺

    // 鎴栬�呭綋鍓嶈繘绋嬬敤鎴蜂笉鏄�瓒呯骇鐢ㄦ埛锛屽垯琛ㄦ槑褰撳墠杩涚▼娌℃湁鏉冨姏杩愯�岃繖涓�鎵ц�屾枃浠躲�備簬鏄�缃�涓嶅彲

    // 鎵ц�屽嚭閿欑爜锛屽苟璺宠浆鍒�exec_error2澶勫幓浣滈��鍑哄�勭悊銆�

237         if (current->euid == inode->i_uid)

238                 i >>= 6;

239         else if (in_group_p(inode->i_gid))

240                 i >>= 3;

241         if (!(i & 1) &&

242             !((inode->i_mode & 0111) && suser())) {

243                 retval = -ENOEXEC;

244                 goto exec_error2;

245         }

    // 绋嬪簭鎵ц�屽埌杩欓噷锛岃�存槑褰撳墠杩涚▼鏈夎繍琛屾寚瀹氭墽琛屾枃浠剁殑鏉冮檺銆傚洜姝や粠杩欓噷寮�濮嬫垜浠�闇�瑕佸彇鍑�

    // 鎵ц�屾枃浠跺ご閮ㄦ暟鎹�骞舵牴鎹�鍏朵腑鐨勪俊鎭�鏉ュ垎鏋愯�剧疆杩愯�岀幆澧冿紝鎴栬�呰繍琛屽彟涓�涓�shell绋嬪簭鏉ユ墽

    // 琛岃剼鏈�绋嬪簭銆傞�栧厛璇诲彇鎵ц�屾枃浠剁��1鍧楁暟鎹�鍒伴珮閫熺紦鍐插潡涓�銆� 骞跺�嶅埗缂撳啿鍧楁暟鎹�鍒�ex涓�銆�

    // 濡傛灉鎵ц�屾枃浠跺紑濮嬬殑涓や釜瀛楄妭鏄�瀛楃��'#!'锛屽垯璇存槑鎵ц�屾枃浠舵槸涓�涓�鑴氭湰鏂囨湰鏂囦欢銆傚�傛灉鎯宠��

    // 琛岃剼鏈�鏂囦欢锛屾垜浠�灏遍渶瑕佹墽琛岃剼鏈�鏂囦欢鐨勮В閲婄▼搴忥紙渚嬪��shell绋嬪簭锛夈�傞�氬父鑴氭湰鏂囦欢鐨勭��

    // 涓�琛屾枃鏈�涓衡��#锛�/bin/bash鈥濄�傚畠鎸囨槑浜嗚繍琛岃剼鏈�鏂囦欢闇�瑕佺殑瑙ｉ噴绋嬪簭銆傝繍琛屾柟娉曟槸浠庤剼鏈�

    // 鏂囦欢绗�1琛岋紙甯﹀瓧绗�'#!'锛変腑鍙栧嚭鍏朵腑鐨勮В閲婄▼搴忓悕鍙婂悗闈㈢殑鍙傛暟锛堣嫢鏈夌殑璇濓級锛岀劧鍚庡皢杩�

    // 浜涘弬鏁板拰鑴氭湰鏂囦欢鍚嶆斁杩涙墽琛屾枃浠讹紙姝ゆ椂鏄�瑙ｉ噴绋嬪簭锛夌殑鍛戒护琛屽弬鏁扮┖闂翠腑銆傚湪杩欎箣鍓嶆垜浠�

    // 褰撶劧闇�瑕佸厛鎶婂嚱鏁版寚瀹氱殑鍘熸湁鍛戒护琛屽弬鏁板拰鐜�澧冨瓧绗︿覆鏀惧��128KB绌洪棿涓�锛岃�岃繖閲屽缓绔嬭捣鏉�

    // 鐨勫懡浠よ�屽弬鏁板垯鏀惧埌瀹冧滑鍓嶉潰浣嶇疆澶勶紙鍥犱负鏄�閫嗗悜鏀剧疆锛夈�傛渶鍚庤�╁唴鏍告墽琛岃剼鏈�鏂囦欢鐨勮В閲�

    // 绋嬪簭銆備笅闈㈠氨鏄�鍦ㄨ�剧疆濂借В閲婄▼搴忕殑鑴氭湰鏂囦欢鍚嶇瓑鍙傛暟鍚庯紝鍙栧嚭瑙ｉ噴绋嬪簭鐨�i鑺傜偣骞惰烦杞�鍒�

    // 229琛屽幓鎵ц�岃В閲婄▼搴忋�傜敱浜庢垜浠�闇�瑕佽烦杞�鍒版墽琛岃繃鐨勪唬鐮�229琛屽幓锛屽洜姝ゅ湪涓嬮潰纭�璁ゅ苟澶�

    // 鐞嗕簡鑴氭湰鏂囦欢涔嬪悗闇�瑕佽�剧疆涓�涓�绂佹�㈠啀娆℃墽琛屼笅闈㈢殑鑴氭湰澶勭悊浠ｇ爜鏍囧織sh_bang 銆傚湪鍚庨潰鐨�

    // 浠ｇ爜涓�璇ユ爣蹇椾篃鐢ㄦ潵琛ㄧず鎴戜滑宸茬粡璁剧疆濂芥墽琛屾枃浠剁殑鍛戒护琛屽弬鏁帮紝涓嶈�侀噸澶嶈�剧疆銆�

246         if (!(bh = bread(inode->i_dev,inode->i_zone[0]))) {

247                 retval = -EACCES;

248                 goto exec_error2;

249         }

250         ex = *((struct exec *) bh->b_data);     /* read exec-header */

251         if ((bh->b_data[0] == '#') && (bh->b_data[1] == '!') && (!sh_bang)) {

252                 /*

253                  * This section does the #! interpretation.

254                  * Sorta complicated, but hopefully it will work.  -TYT

255                  */

                    /*

                     * 杩欓儴鍒嗗�勭悊瀵�'#!'鐨勮В閲婏紝鏈変簺澶嶆潅锛屼絾甯屾湜鑳藉伐浣溿��-TYT

                     */

256

257                 char buf[128], *cp, *interp, *i_name, *i_arg;

258                 unsigned long old_fs;

259

    // 浠庤繖閲屽紑濮嬶紝鎴戜滑浠庤剼鏈�鏂囦欢涓�鎻愬彇瑙ｉ噴绋嬪簭鍚嶅強鍏跺弬鏁帮紝骞舵妸瑙ｉ噴绋嬪簭鍚嶃�佽В閲婄▼搴忕殑鍙傛暟

    // 鍜岃剼鏈�鏂囦欢鍚嶇粍鍚堟斁鍏ョ幆澧冨弬鏁板潡涓�銆傞�栧厛澶嶅埗鑴氭湰鏂囦欢澶�1琛屽瓧绗�'#!'鍚庨潰鐨勫瓧绗︿覆鍒�buf

    // 涓�锛屽叾涓�鍚�鏈夎剼鏈�瑙ｉ噴绋嬪簭鍚嶏紙渚嬪��/bin/sh锛夛紝涔熷彲鑳借繕鍖呭惈瑙ｉ噴绋嬪簭鐨勫嚑涓�鍙傛暟銆傜劧鍚庡��

    // buf涓�鐨勫唴瀹硅繘琛屽�勭悊銆傚垹闄ゅ紑濮嬬殑绌烘牸銆佸埗琛ㄧ�︺��

260                 strncpy(buf, bh->b_data+2, 127);

261                 brelse(bh);

262                 iput(inode);                     // 閲婃斁缂撳啿鍧楀苟鏀惧洖鑴氭湰鏂囦欢i鑺傜偣銆�

263                 buf[127] = '\0';

264                 if (cp = strchr(buf, '\n')) {

265                         *cp = '\0';       // 绗�1涓�鎹㈣�岀�︽崲鎴�NULL骞跺幓鎺夌┖鏍煎埗琛ㄧ�︺��

266                         for (cp = buf; (*cp == ' ') || (*cp == '\t'); cp++);

267                 }

268                 if (!cp || *cp == '\0') {        // 鑻ヨ�ヨ�屾病鏈夊叾浠栧唴瀹癸紝鍒欏嚭閿欍��

269                         retval = -ENOEXEC;       /* No interpreter name found */

270                         goto exec_error1;        /* 娌℃湁鎵惧埌鑴氭湰瑙ｉ噴绋嬪簭鍚� */

271                 }

    // 姝ゆ椂鎴戜滑寰楀埌浜嗗紑澶存槸鑴氭湰瑙ｉ噴绋嬪簭鍚嶇殑涓�琛屽唴瀹癸紙瀛楃�︿覆锛夈�備笅闈㈠垎鏋愯�ヨ�屻�傞�栧厛鍙栫��涓�涓�

    // 瀛楃�︿覆锛屽畠搴旇�ユ槸瑙ｉ噴绋嬪簭鍚嶏紝姝ゆ椂i_name鎸囧悜璇ュ悕绉般�傝嫢瑙ｉ噴绋嬪簭鍚嶅悗杩樻湁瀛楃�︼紝鍒欏畠浠�搴�

    // 璇ユ槸瑙ｉ噴绋嬪簭鐨勫弬鏁颁覆锛屼簬鏄�浠�i_arg鎸囧悜璇ヤ覆銆�

272                 interp = i_name = cp;

273                 i_arg = 0;

274                 for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++) {

275                         if (*cp == '/')

276                                 i_name = cp+1;

277                 }

278                 if (*cp) {

279                         *cp++ = '\0';            // 瑙ｉ噴绋嬪簭鍚嶅熬娣诲姞NULL瀛楃�︺��

280                         i_arg = cp;              // i_arg鎸囧悜瑙ｉ噴绋嬪簭鍙傛暟銆�

281                 }

282                 /*

283                  * OK, we've parsed out the interpreter name and

284                  * (optional) argument.

285                  */

                    /*

                     * OK锛屾垜浠�宸茬粡瑙ｆ瀽鍑鸿В閲婄▼搴忕殑鏂囦欢鍚嶄互鍙�(鍙�閫夌殑)鍙傛暟銆�

                     */

    // 鐜板湪鎴戜滑瑕佹妸涓婇潰瑙ｆ瀽鍑烘潵鐨勮В閲婄▼搴忓悕i_name 鍙婂叾鍙傛暟i_arg 鍜岃剼鏈�鏂囦欢鍚嶄綔涓鸿В閲婄��

    // 搴忕殑鍙傛暟鏀捐繘鐜�澧冨拰鍙傛暟鍧椾腑銆備笉杩囬�栧厛鎴戜滑闇�瑕佹妸鍑芥暟鎻愪緵鐨勫師鏉ヤ竴浜涘弬鏁板拰鐜�澧冨瓧绗︿��

    // 鍏堟斁杩涘幓锛岀劧鍚庡啀鏀捐繖閲岃В鏋愬嚭鏉ョ殑銆備緥濡傚�逛簬鍛戒护琛屽弬鏁版潵璇达紝濡傛灉鍘熸潵鐨勫弬鏁版��"-arg1

    //  -arg2"銆佽В閲婄▼搴忓悕鏄�"bash"銆佸叾鍙傛暟鏄�"-iarg1 -iarg2"銆佽剼鏈�鏂囦欢鍚嶏紙鍗冲師鏉ョ殑鎵ц�屾枃

    // 浠跺悕锛夋槸"example.sh"锛岄偅涔堝湪鏀惧叆杩欓噷鐨勫弬鏁颁箣鍚庯紝鏂扮殑鍛戒护琛岀被浼间簬杩欐牱锛�

    //         鈥�bash -iarg1 -iarg2 example.sh -arg1 -arg2鈥�

    // 杩欓噷鎴戜滑鎶�sh_bang鏍囧織缃�涓婏紝鐒跺悗鎶婂嚱鏁板弬鏁版彁渚涚殑鍘熸湁鍙傛暟鍜岀幆澧冨瓧绗︿覆鏀惧叆鍒扮┖闂翠腑銆�

    // 鐜�澧冨瓧绗︿覆鍜屽弬鏁颁釜鏁板垎鍒�鏄�envc 鍜�argc-1涓�銆傚皯澶嶅埗鐨勪竴涓�鍘熸湁鍙傛暟鏄�鍘熸潵鐨勬墽琛屾枃浠�

    // 鍚嶏紝鍗宠繖閲岀殑鑴氭湰鏂囦欢鍚嶃��[[?? 鍙�浠ョ湅鍑猴紝瀹為檯涓婃垜浠�涓嶉渶瑕佸幓鍙﹁�屽�勭悊鑴氭湰鏂囦欢鍚嶏紝鍗宠繖

    // 閲屽畬鍏ㄥ彲浠ュ�嶅��argc涓�鍙傛暟锛屽寘鎷�鍘熸潵鎵ц�屾枃浠跺悕锛堝嵆鐜板湪鐨勮剼鏈�鏂囦欢鍚嶏級銆傚洜涓哄畠浣嶄簬鍚�

    // 涓�涓�浣嶇疆涓� ]]銆傛敞鎰忥紒杩欓噷鎸囬拡p闅忕潃澶嶅埗淇℃伅澧炲姞鑰岄�愭笎鍚戝皬鍦板潃鏂瑰悜绉诲姩锛屽洜姝よ繖涓や釜

    // 澶嶅埗涓插嚱鏁版墽琛屽畬鍚庯紝鐜�澧冨弬鏁颁覆淇℃伅鍧椾綅浜庣▼搴忓懡浠よ�屽弬鏁颁覆淇℃伅鍧楃殑涓婃柟锛屽苟涓� p鎸囧悜

    // 绋嬪簭鐨勭��1涓�鍙傛暟涓层��copy_strings()鏈�鍚庝竴涓�鍙傛暟锛�0锛夋寚鏄庡弬鏁板瓧绗︿覆鍦ㄧ敤鎴风┖闂淬��

286                 if (sh_bang++ == 0) {

287                         p = copy_strings(envc, envp, page, p, 0);

288                         p = copy_strings(--argc, argv+1, page, p, 0);

289                 }

290                 /*

291                  * Splice in (1) the interpreter's name for argv[0]

292                  *           (2) (optional) argument to interpreter

293                  *           (3) filename of shell script

294                  *

295                  * This is done in reverse order, because of how the

296                  * user environment and arguments are stored.

297                  */

                    /*

                     * 鎷兼帴 (1) argv[0]涓�鏀捐В閲婄▼搴忕殑鍚嶇��

                     *      (2) (鍙�閫夌殑)瑙ｉ噴绋嬪簭鐨勫弬鏁�

                     *      (3) 鑴氭湰绋嬪簭鐨勫悕绉�

                     *

                     * 杩欐槸浠ラ�嗗簭杩涜�屽�勭悊鐨勶紝鏄�鐢变簬鐢ㄦ埛鐜�澧冨拰鍙傛暟鐨勫瓨鏀炬柟寮忛�犳垚鐨勩��

                     */

    // 鎺ョ潃鎴戜滑閫嗗悜澶嶅埗鑴氭湰鏂囦欢鍚嶃�佽В閲婄▼搴忕殑鍙傛暟鍜岃В閲婄▼搴忔枃浠跺悕鍒板弬鏁板拰鐜�澧冪┖闂翠腑銆�

    // 鑻ュ嚭閿欙紝鍒欑疆鍑洪敊鐮侊紝璺宠浆鍒�exec_error1銆傚彟澶栵紝鐢变簬鏈�鍑芥暟鍙傛暟鎻愪緵鐨勮剼鏈�鏂囦欢鍚�

    // filename鍦ㄧ敤鎴风┖闂达紝浣嗚繖閲岃祴浜�copy_strings()鐨勮剼鏈�鏂囦欢鍚嶇殑鎸囬拡鍦ㄥ唴鏍哥┖闂达紝鍥�

    // 姝よ繖涓�澶嶅埗瀛楃�︿覆鍑芥暟鐨勬渶鍚庝竴涓�鍙傛暟锛堝瓧绗︿覆鏉ユ簮鏍囧織锛夐渶瑕佽��璁剧疆鎴�1銆傝嫢瀛楃�︿覆鍦�

    // 鍐呮牳绌洪棿锛屽垯copy_strings()鐨勬渶鍚庝竴涓�鍙傛暟瑕佽�剧疆鎴�2锛屽�備笅闈㈢殑绗�301銆�304琛屻��

298                 p = copy_strings(1, &filename, page, p, 1);

299                 argc++;

300                 if (i_arg) {                      // 澶嶅埗瑙ｉ噴绋嬪簭鐨勫�氫釜鍙傛暟銆�

301                         p = copy_strings(1, &i_arg, page, p, 2);

302                         argc++;

303                 }

304                 p = copy_strings(1, &i_name, page, p, 2);

305                 argc++;

306                 if (!p) {

307                         retval = -ENOMEM;

308                         goto exec_error1;

309                 }

310                 /*

311                  * OK, now restart the process with the interpreter's inode.

312                  */

                    /*

                     * OK锛岀幇鍦ㄤ娇鐢ㄨВ閲婄▼搴忕殑i鑺傜偣閲嶅惎杩涚▼銆�

                     */

    // 鏈�鍚庢垜浠�鍙栧緱瑙ｉ噴绋嬪簭鐨�i鑺傜偣鎸囬拡锛岀劧鍚庤烦杞�鍒�204琛屽幓鎵ц�岃В閲婄▼搴忋�備负浜嗚幏寰楄В閲婄▼

    // 搴忕殑i鑺傜偣锛屾垜浠�闇�瑕佷娇鐢�namei()鍑芥暟锛屼絾鏄�璇ュ嚱鏁版墍浣跨敤鐨勫弬鏁帮紙鏂囦欢鍚嶏級鏄�浠庣敤鎴锋��

    // 鎹�绌洪棿寰楀埌鐨勶紝鍗充粠娈靛瘎瀛樺��fs鎵�鎸囩┖闂翠腑鍙栧緱銆傚洜姝ゅ湪璋冪敤namei()鍑芥暟涔嬪墠鎴戜滑闇�瑕�

    // 鍏堜复鏃惰��fs鎸囧悜鍐呮牳鏁版嵁绌洪棿锛屼互璁╁嚱鏁拌兘浠庡唴鏍哥┖闂村緱鍒拌В閲婄▼搴忓悕锛屽苟鍦�namei()

    // 杩斿洖鍚庢仮澶�fs鐨勯粯璁よ�剧疆銆傚洜姝よ繖閲屾垜浠�鍏堜复鏃朵繚瀛樺��fs娈靛瘎瀛樺櫒锛堝師鎸囧悜鐢ㄦ埛鏁版嵁娈碉級

    // 鐨勫�硷紝灏嗗叾璁剧疆鎴愭寚鍚戝唴鏍告暟鎹�娈碉紝鐒跺悗鍙栬В閲婄▼搴忕��i鑺傜偣銆備箣鍚庡啀鎭㈠��fs鐨勫師鍊笺�傚苟

    // 璺宠浆鍒�restart_interp锛�204琛岋級澶勯噸鏂板�勭悊鏂扮殑鎵ц�屾枃浠� -- 鑴氭湰鏂囦欢鐨勮В閲婄▼搴忋��

313                 old_fs = get_fs();

314                 set_fs(get_ds());

315                 if (!(inode=namei(interp))) {        /* get executables inode */

316                         set_fs(old_fs);              /* 鍙栧緱瑙ｉ噴绋嬪簭鐨�i鑺傜偣 */

317                         retval = -ENOENT;

318                         goto exec_error1;

319                 }

320                 set_fs(old_fs);

321                 goto restart_interp;

322         }

 

    // 姝ゆ椂缂撳啿鍧椾腑鐨勬墽琛屾枃浠跺ご缁撴瀯鏁版嵁宸茬粡澶嶅埗鍒颁簡ex 涓�銆� 浜庢槸鍏堥噴鏀捐�ョ紦鍐插潡锛屽苟寮�濮嬪��

    // ex涓�鐨勬墽琛屽ご淇℃伅杩涜�屽垽鏂�澶勭悊銆傚�逛��Linux 0.12鍐呮牳鏉ヨ�达紝瀹冧粎鏀�鎸�ZMAGIC鎵ц�屾枃浠舵��

    // 寮忥紝骞朵笖鎵ц�屾枃浠朵唬鐮侀兘浠庨�昏緫鍦板潃0 寮�濮嬫墽琛岋紝鍥犳�や笉鏀�鎸佸惈鏈変唬鐮佹垨鏁版嵁閲嶅畾浣嶄俊鎭�鐨�

    // 鎵ц�屾枃浠躲�傚綋鐒讹紝濡傛灉鎵ц�屾枃浠跺疄鍦ㄥお澶ф垨鑰呮墽琛屾枃浠舵畫缂轰笉鍏�锛岄偅涔堟垜浠�涔熶笉鑳借繍琛屽畠銆�

    // 鍥犳�ゅ�逛簬涓嬪垪鎯呭喌灏嗕笉鎵ц�岀▼搴忥細濡傛灉鎵ц�屾枃浠朵笉鏄�闇�姹傞〉鍙�鎵ц�屾枃浠讹紙ZMAGIC锛夈�佹垨鑰呬唬

    // 鐮佸拰鏁版嵁閲嶅畾浣嶉儴鍒嗛暱搴︿笉绛変簬0銆佹垨鑰�(浠ｇ爜娈�+鏁版嵁娈�+鍫�) 闀垮害瓒呰繃50MB銆佹垨鑰呮墽琛屾枃浠�

    // 闀垮害灏忎簬 (浠ｇ爜娈�+鏁版嵁娈�+绗﹀彿琛ㄩ暱搴�+鎵ц�屽ご閮ㄥ��) 闀垮害鐨勬�诲拰銆�

323         brelse(bh);

324         if (N_MAGIC(ex) != ZMAGIC || ex.a_trsize || ex.a_drsize ||

325                 ex.a_text+ex.a_data+ex.a_bss>0x3000000 ||

326                 inode->i_size < ex.a_text+ex.a_data+ex.a_syms+N_TXTOFF(ex)) {

327                 retval = -ENOEXEC;

328                 goto exec_error2;

329         }

    // 鍙﹀�栵紝濡傛灉鎵ц�屾枃浠朵腑浠ｇ爜寮�濮嬪�勬病鏈変綅浜�1涓�椤甸潰锛�1024瀛楄妭锛夎竟鐣屽�勶紝鍒欎篃涓嶈兘鎵ц�屻��

    // 鍥犱负闇�姹傞〉锛�Demand paging锛夋妧鏈�瑕佹眰鍔犺浇鎵ц�屾枃浠跺唴瀹规椂浠ラ〉闈�涓哄崟浣嶏紝鍥犳�よ�佹眰鎵ц��

    // 鏂囦欢鏄犲儚涓�浠ｇ爜鍜屾暟鎹�閮戒粠椤甸潰杈圭晫澶勫紑濮嬨��

330         if (N_TXTOFF(ex) != BLOCK_SIZE) {

331                 printk("%s: N_TXTOFF != BLOCK_SIZE. See a.out.h.", filename);

332                 retval = -ENOEXEC;

333                 goto exec_error2;

334         }

    // 濡傛灉sh_bang鏍囧織娌℃湁璁剧疆锛屽垯澶嶅埗鎸囧畾涓�鏁扮殑鍛戒护琛屽弬鏁板拰鐜�澧冨瓧绗︿覆鍒板弬鏁板拰鐜�澧冪┖闂�

    // 涓�銆傝嫢sh_bang鏍囧織宸茬粡璁剧疆锛屽垯琛ㄦ槑鏄�灏嗚繍琛岃剼鏈�瑙ｉ噴绋嬪簭锛屾�ゆ椂鐜�澧冨彉閲忛〉闈㈠凡缁忓�嶅埗锛�

    // 鏃犻』鍐嶅�嶅埗銆傚悓鏍凤紝鑻�sh_bang娌℃湁缃�浣嶈�岄渶瑕佸�嶅埗鐨勮瘽锛岄偅涔堟�ゆ椂鎸囬拡p闅忕潃澶嶅埗淇℃伅澧�

    // 鍔犺�岄�愭笎鍚戝皬鍦板潃鏂瑰悜绉诲姩锛屽洜姝よ繖涓や釜澶嶅埗涓插嚱鏁版墽琛屽畬鍚庯紝鐜�澧冨弬鏁颁覆淇℃伅鍧椾綅浜庣▼搴�

    // 鍙傛暟涓蹭俊鎭�鍧楃殑涓婃柟锛屽苟涓�p鎸囧悜绋嬪簭鐨勭��1涓�鍙傛暟涓层�備簨瀹炰笂锛�p鏄�128KB鍙傛暟鍜岀幆澧冪┖

    // 闂翠腑鐨勫亸绉诲�笺�傚洜姝ゅ�傛��p=0锛屽垯琛ㄧず鐜�澧冨彉閲忎笌鍙傛暟绌洪棿椤甸潰宸茬粡琚�鍗犳弧锛屽�圭撼涓嶄笅浜嗐��

335         if (!sh_bang) {

336                 p = copy_strings(envc,envp,page,p,0);

337                 p = copy_strings(argc,argv,page,p,0);

338                 if (!p) {

339                         retval = -ENOMEM;

340                         goto exec_error2;

341                 }

342         }

343 /* OK, This is the point of no return */

344 /* note that current->library stays unchanged by an exec */

    /* OK锛屼笅闈㈠紑濮嬪氨娌℃湁杩斿洖鐨勫湴鏂逛簡 */

    // 鍓嶉潰鎴戜滑閽堝�瑰嚱鏁板弬鏁版彁渚涚殑淇℃伅瀵归渶瑕佽繍琛屾墽琛屾枃浠剁殑鍛戒护琛屽弬鏁板拰鐜�澧冪┖闂磋繘琛屼簡璁剧疆锛�

    // 浣嗚繕娌℃湁涓烘墽琛屾枃浠跺仛杩囦粈涔堝疄璐ㄦ�х殑宸ヤ綔锛屽嵆杩樻病鏈夊仛杩囦负鎵ц�屾枃浠跺垵濮嬪寲杩涚▼浠诲姟缁撴��

    // 淇℃伅銆佸缓绔嬮〉琛ㄧ瓑宸ヤ綔銆傜幇鍦ㄦ垜浠�灏辨潵鍋氳繖浜涘伐浣溿�傜敱浜庢墽琛屾枃浠剁洿鎺ヤ娇鐢ㄥ綋鍓嶈繘绋嬬殑鈥滆函

    // 澹斥�濓紝鍗冲綋鍓嶈繘绋嬪皢琚�鏀归�犳垚鎵ц�屾枃浠剁殑杩涚▼锛屽洜姝ゆ垜浠�闇�瑕侀�栧厛閲婃斁褰撳墠杩涚▼鍗犵敤鐨勬煇浜�

    // 绯荤粺璧勬簮锛屽寘鎷�鍏抽棴鎸囧畾鐨勫凡鎵撳紑鏂囦欢銆佸崰鐢ㄧ殑椤佃〃鍜屽唴瀛橀〉闈㈢瓑銆傜劧鍚庢牴鎹�鎵ц�屾枃浠跺ご缁�

    // 鏋勪俊鎭�淇�鏀瑰綋鍓嶈繘绋嬩娇鐢ㄧ殑灞�閮ㄦ弿杩扮�﹁��LDT涓�鎻忚堪绗︾殑鍐呭�癸紝閲嶆柊璁剧疆浠ｇ爜娈靛拰鏁版嵁娈垫弿

    // 杩扮�︾殑闄愰暱锛屽啀鍒╃敤鍓嶉潰澶勭悊寰楀埌鐨�e_uid鍜�e_gid绛変俊鎭�鏉ヨ�剧疆杩涚▼浠诲姟缁撴瀯涓�鐩稿叧鐨勫��

    // 娈点�傛渶鍚庢妸鎵ц�屾湰娆＄郴缁熻皟鐢ㄧ▼搴忕殑杩斿洖鍦板潃 eip[]鎸囧悜鎵ц�屾枃浠朵腑浠ｇ爜鐨勮捣濮嬩綅缃�澶勩�傝繖

    // 鏍峰綋鏈�绯荤粺璋冪敤閫�鍑鸿繑鍥炲悗灏变細鍘昏繍琛屾柊鎵ц�屾枃浠剁殑浠ｇ爜浜嗐�傛敞鎰忥紝铏界劧姝ゆ椂鏂版墽琛屾枃浠朵唬

    // 鐮佸拰鏁版嵁杩樻病鏈変粠鏂囦欢涓�鍔犺浇鍒板唴瀛樹腑锛屼絾鍏跺弬鏁板拰鐜�澧冨潡宸茬粡鍦�copy_strings() 涓�浣跨��

    // get_free_page()鍒嗛厤浜嗙墿鐞嗗唴瀛橀〉鏉ヤ繚瀛樻暟鎹�锛屽苟鍦�change_ldt()鍑芥暟涓�浣跨��put_page()

    // 鍒颁簡杩涚▼閫昏緫绌洪棿鐨勬湯绔�澶勩�傚彟澶栵紝鍦�create_tables()涓�涔熶細鐢变簬鍦ㄧ敤鎴锋爤涓婂瓨鏀惧弬鏁�

    // 鍜岀幆澧冩寚閽堣〃鑰屽紩璧风己椤靛紓甯革紝浠庤�屽唴瀛樼�＄悊绋嬪簭涔熶細灏辨�や负鐢ㄦ埛鏍堢┖闂存槧灏勭墿鐞嗗唴瀛橀〉銆�

    //

    // 杩欓噷鎴戜滑棣栧厛鏀惧洖杩涚▼鍘熸墽琛岀▼搴忕殑i鑺傜偣锛屽苟涓旇�╄繘绋�executable 瀛楁�垫寚鍚戞柊鎵ц�屾枃浠�

    // 鐨�i鑺傜偣銆傜劧鍚庡�嶄綅鍘熻繘绋嬬殑鎵�鏈変俊鍙峰�勭悊鍙ユ焺锛屼絾瀵逛��SIG_IGN鍙ユ焺鏃犻』澶嶄綅銆傚啀鏍规嵁璁�

    // 瀹氱殑鎵ц�屾椂鍏抽棴鏂囦欢鍙ユ焺锛�close_on_exec锛変綅鍥炬爣蹇楋紝鍏抽棴鎸囧畾鐨勬墦寮�鏂囦欢骞跺�嶄綅璇ユ爣蹇椼��

345         if (current->executable)

346                 iput(current->executable);

347         current->executable = inode;

348         current->signal = 0;

349         for (i=0 ; i<32 ; i++) {

350                 current->sigaction[i].sa_mask = 0;

351                 current->sigaction[i].sa_flags = 0;

352                 if (current->sigaction[i].sa_handler != SIG_IGN)

353                         current->sigaction[i].sa_handler = NULL;

354         }

355         for (i=0 ; i<NR_OPEN ; i++)

356                 if ((current->close_on_exec>>i)&1)

357                         sys_close(i);

358         current->close_on_exec = 0;

    // 鐒跺悗鏍规嵁褰撳墠杩涚▼鎸囧畾鐨勫熀鍦板潃鍜岄檺闀匡紝閲婃斁鍘熸潵绋嬪簭鐨勪唬鐮佹�靛拰鏁版嵁娈垫墍瀵瑰簲鐨勫唴瀛橀〉琛�

    // 鎸囧畾鐨勭墿鐞嗗唴瀛橀〉闈㈠強椤佃〃鏈�韬�銆傛�ゆ椂鏂版墽琛屾枃浠跺苟娌℃湁鍗犵敤涓诲唴瀛樺尯浠讳綍椤甸潰锛屽洜姝ゅ湪澶�

    // 鐞嗗櫒鐪熸�ｈ繍琛屾柊鎵ц�屾枃浠朵唬鐮佹椂灏变細寮曡捣缂洪〉寮傚父涓�鏂�锛屾�ゆ椂鍐呭瓨绠＄悊绋嬪簭鍗充細鎵ц�岀己椤靛��

    // 鐞嗚�屼负鏂版墽琛屾枃浠剁敵璇峰唴瀛橀〉闈㈠拰璁剧疆鐩稿叧椤佃〃椤癸紝骞朵笖鎶婄浉鍏虫墽琛屾枃浠堕〉闈㈣�诲叆鍐呭瓨涓�銆�

    // 濡傛灉鈥滀笂娆′换鍔′娇鐢ㄤ簡鍗忓�勭悊鍣ㄢ�濇寚鍚戠殑鏄�褰撳墠杩涚▼锛屽垯灏嗗叾缃�绌猴紝骞跺�嶄綅浣跨敤浜嗗崗澶勭悊鍣�

    // 鐨勬爣蹇椼��

359         free_page_tables(get_base(current->ldt[1]),get_limit(0x0f));

360         free_page_tables(get_base(current->ldt[2]),get_limit(0x17));

361         if (last_task_used_math == current)

362                 last_task_used_math = NULL;

363         current->used_math = 0;

    // 鐒跺悗鎴戜滑鏍规嵁鏂版墽琛屾枃浠跺ご缁撴瀯涓�鐨勪唬鐮侀暱搴﹀瓧娈� a_text 鐨勫�间慨鏀瑰眬閮ㄨ〃涓�鎻忚堪绗﹀熀鍧�鍜�

    // 娈甸檺闀匡紝骞跺皢128KB 鐨勫弬鏁板拰鐜�澧冪┖闂撮〉闈㈡斁缃�鍦ㄦ暟鎹�娈垫湯绔�銆傛墽琛屼笅闈㈣��鍙ヤ箣鍚庯紝p姝ゆ椂

    // 鏇存敼鎴愪互鏁版嵁娈佃捣濮嬪�勪负鍘熺偣鐨勫亸绉诲�硷紝浣嗕粛鎸囧悜鍙傛暟鍜岀幆澧冪┖闂存暟鎹�寮�濮嬪�勶紝鍗冲凡杞�鎹㈡垚

    // 涓烘爤鎸囬拡鍊笺�傜劧鍚庤皟鐢ㄥ唴閮ㄥ嚱鏁�create_tables() 鍦ㄦ爤绌洪棿涓�鍒涘缓鐜�澧冨拰鍙傛暟鍙橀噺鎸囬拡琛�锛�

    // 渚涚▼搴忕殑main()浣滀负鍙傛暟浣跨敤锛屽苟杩斿洖璇ユ爤鎸囬拡銆�

364         p += change_ldt(ex.a_text,page);

365         p -= LIBRARY_SIZE + MAX_ARG_PAGES*PAGE_SIZE;

366         p = (unsigned long) create_tables((char *)p,argc,envc);

 

    // 鎺ョ潃鍐嶄慨鏀硅繘绋嬪悇瀛楁�靛�间负鏂版墽琛屾枃浠剁殑淇℃伅銆傚嵆浠よ繘绋嬩换鍔＄粨鏋勪唬鐮佸熬瀛楁��end_code绛�

    // 浜庢墽琛屾枃浠剁殑浠ｇ爜娈甸暱搴� a_text锛涙暟鎹�灏惧瓧娈� end_data 绛変簬鎵ц�屾枃浠剁殑浠ｇ爜娈甸暱搴﹀姞鏁�

    // 鎹�娈甸暱搴︼��a_data + a_text锛夛紱骞朵护杩涚▼鍫嗙粨灏惧瓧娈�brk = a_text + a_data + a_bss銆�

    // brk鐢ㄤ簬鎸囨槑杩涚▼褰撳墠鏁版嵁娈碉紙鍖呮嫭鏈�鍒濆�嬪寲鏁版嵁閮ㄥ垎锛夋湯绔�浣嶇疆锛屼緵鍐呮牳涓鸿繘绋嬪垎閰嶅唴瀛�

    // 鏃舵寚瀹氬垎閰嶅紑濮嬩綅缃�銆傜劧鍚庤�剧疆杩涚▼鏍堝紑濮嬪瓧娈典负鏍堟寚閽堟墍鍦ㄩ〉闈�锛屽苟閲嶆柊璁剧疆杩涚▼鐨勬湁鏁�

    // 鐢ㄦ埛id鍜屾湁鏁堢粍id銆�

367         current->brk = ex.a_bss +

368                 (current->end_data = ex.a_data +

369                 (current->end_code = ex.a_text));

370         current->start_stack = p & 0xfffff000;

371         current->suid = current->euid = e_uid;

372         current->sgid = current->egid = e_gid;

    // 鏈�鍚庡皢鍘熻皟鐢ㄧ郴缁熶腑鏂�鐨勭▼搴忓湪鍫嗘爤涓婄殑浠ｇ爜鎸囬拡鏇挎崲涓烘寚鍚戞柊鎵ц�岀▼搴忕殑鍏ュ彛鐐癸紝骞跺皢鏍�

    // 鎸囬拡鏇挎崲涓烘柊鎵ц�屾枃浠剁殑鏍堟寚閽堛�傛�ゅ悗杩斿洖鎸囦护灏嗗脊鍑鸿繖浜涙爤鏁版嵁骞朵娇寰�CPU鍘绘墽琛屾柊鎵ц��

    // 鏂囦欢锛屽洜姝や笉浼氳繑鍥炲埌鍘熻皟鐢ㄧ郴缁熶腑鏂�鐨勭▼搴忎腑鍘讳簡銆�

373         eip[0] = ex.a_entry;    /* eip, magic happens :-) */  /* eip锛岄瓟娉曡捣浣滅敤浜�*/

374         eip[3] = p;             /* stack pointer */           /* esp锛屽爢鏍堟寚閽� */

375         return 0;

376 exec_error2:

377         iput(inode);                       // 鏀惧洖i鑺傜偣銆�

378 exec_error1:

379         for (i=0 ; i<MAX_ARG_PAGES ; i++)

380                 free_page(page[i]);        // 閲婃斁瀛樻斁鍙傛暟鍜岀幆澧冧覆鐨勫唴瀛橀〉闈���

381         return(retval);                    // 杩斿洖鍑洪敊鐮併��

382 }

383