csum-file.c

   1 /*
   2  * csum-file.c
   3  *
   4  * Copyright (C) 2005 Linus Torvalds
   5  *
   6  * Simple file write infrastructure for writing SHA1-summed
   7  * files. Useful when you write a file that you want to be
   8  * able to verify hasn't been messed with afterwards.
   9  */
  10 #include "cache.h"
  11 #include "csum-file.h"
  12
  13 static void sha1flush(struct sha1file *f, unsigned int count)
  14 {
  15         void *buf = f->buffer;
  16
  17         for (;;) {
  18                 int ret = xwrite(f->fd, buf, count);
  19                 if (ret > 0) {
  20                         buf = (char *) buf + ret;
  21                         count -= ret;
  22                         if (count)
  23                                 continue;
  24                         return;
  25                 }
  26                 if (!ret)
  27                         die("sha1 file '%s' write error. Out of diskspace", f->name);
  28                 die("sha1 file '%s' write error (%s)", f->name, strerror(errno));
  29         }
  30 }
  31
  32 int sha1close(struct sha1file *f, unsigned char *result, int final)
  33 {
  34         int fd;
  35         unsigned offset = f->offset;
  36         if (offset) {
  37                 SHA1_Update(&f->ctx, f->buffer, offset);
  38                 sha1flush(f, offset);
  39                 f->offset = 0;
  40         }
  41         if (final) {
  42                 /* write checksum and close fd */
  43                 SHA1_Final(f->buffer, &f->ctx);
  44                 if (result)
  45                         hashcpy(result, f->buffer);
  46                 sha1flush(f, 20);
  47                 if (close(f->fd))
  48                         die("%s: sha1 file error on close (%s)",
  49                             f->name, strerror(errno));
  50                 fd = 0;
  51         } else
  52                 fd = f->fd;
  53         free(f);
  54         return fd;
  55 }
  56
  57 int sha1write(struct sha1file *f, void *buf, unsigned int count)
  58 {
  59         if (f->do_crc)
  60                 f->crc32 = crc32(f->crc32, buf, count);
  61         while (count) {
  62                 unsigned offset = f->offset;
  63                 unsigned left = sizeof(f->buffer) - offset;
  64                 unsigned nr = count > left ? left : count;
  65
  66                 memcpy(f->buffer + offset, buf, nr);
  67                 count -= nr;
  68                 offset += nr;
  69                 buf = (char *) buf + nr;
  70                 left -= nr;
  71                 if (!left) {
  72                         SHA1_Update(&f->ctx, f->buffer, offset);
  73                         sha1flush(f, offset);
  74                         offset = 0;
  75                 }
  76                 f->offset = offset;
  77         }
  78         return 0;
  79 }
  80
  81 struct sha1file *sha1fd(int fd, const char *name)
  82 {
  83         struct sha1file *f;
  84         unsigned len;
  85
  86         f = xmalloc(sizeof(*f));
  87
  88         len = strlen(name);
  89         if (len >= PATH_MAX)
  90                 die("you wascally wabbit, you");
  91         f->namelen = len;
  92         memcpy(f->name, name, len+1);
  93
  94         f->fd = fd;
  95         f->error = 0;
  96         f->offset = 0;
  97         f->do_crc = 0;
  98         SHA1_Init(&f->ctx);
  99         return f;
 100 }
 101
 102 void crc32_begin(struct sha1file *f)
 103 {
 104         f->crc32 = crc32(0, Z_NULL, 0);
 105         f->do_crc = 1;
 106 }
 107
 108 uint32_t crc32_end(struct sha1file *f)
 109 {
 110         f->do_crc = 0;
 111         return f->crc32;
 112 }