зеркало из https://github.com/microsoft/git.git
82 строки
1.9 KiB
C
82 строки
1.9 KiB
C
#include "cache.h"
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#include "refs.h"
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static const char git_update_ref_usage[] = "git-update-ref <refname> <value> [<oldval>]";
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static int re_verify(const char *path, unsigned char *oldsha1, unsigned char *currsha1)
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{
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char buf[40];
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int fd = open(path, O_RDONLY), nr;
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if (fd < 0)
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return -1;
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nr = read(fd, buf, 40);
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close(fd);
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if (nr != 40 || get_sha1_hex(buf, currsha1) < 0)
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return -1;
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return memcmp(oldsha1, currsha1, 20) ? -1 : 0;
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}
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int main(int argc, char **argv)
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{
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char *hex;
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const char *refname, *value, *oldval, *path, *lockpath;
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unsigned char sha1[20], oldsha1[20], currsha1[20];
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int fd, written;
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setup_git_directory();
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if (argc < 3 || argc > 4)
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usage(git_update_ref_usage);
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refname = argv[1];
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value = argv[2];
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oldval = argv[3];
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if (get_sha1(value, sha1) < 0)
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die("%s: not a valid SHA1", value);
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memset(oldsha1, 0, 20);
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if (oldval && get_sha1(oldval, oldsha1) < 0)
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die("%s: not a valid old SHA1", oldval);
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path = resolve_ref(git_path("%s", refname), currsha1, !!oldval);
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if (!path)
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die("No such ref: %s", refname);
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if (oldval) {
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if (memcmp(currsha1, oldsha1, 20))
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die("Ref %s changed to %s", refname, sha1_to_hex(currsha1));
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/* Nothing to do? */
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if (!memcmp(oldsha1, sha1, 20))
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exit(0);
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}
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path = strdup(path);
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lockpath = mkpath("%s.lock", path);
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fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
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if (fd < 0)
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die("Unable to create %s", lockpath);
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hex = sha1_to_hex(sha1);
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hex[40] = '\n';
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written = write(fd, hex, 41);
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close(fd);
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if (written != 41) {
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unlink(lockpath);
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die("Unable to write to %s", lockpath);
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}
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/*
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* Re-read the ref after getting the lock to verify
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*/
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if (oldval && re_verify(path, oldsha1, currsha1) < 0) {
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unlink(lockpath);
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die("Ref lock failed");
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}
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/*
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* Finally, replace the old ref with the new one
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*/
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if (rename(lockpath, path) < 0) {
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unlink(lockpath);
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die("Unable to create %s", path);
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}
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return 0;
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}
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