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 "progress.h"
  12 #include "csum-file.h"
  13
  14 static void sha1flush(struct sha1file *f, unsigned int count)
  15 {
  16         void *buf = f->buffer;
  17
  18         for (;;) {
  19                 int ret = xwrite(f->fd, buf, count);
  20                 if (ret > 0) {
  21                         f->total += ret;
  22                         display_throughput(f->tp, f->total);
  23                         buf = (char *) buf + ret;
  24                         count -= ret;
  25                         if (count)
  26                                 continue;
  27                         return;
  28                 }
  29                 if (!ret)
  30                         die("sha1 file '%s' write error. Out of diskspace", f->name);
  31                 die("sha1 file '%s' write error (%s)", f->name, strerror(errno));
  32         }
  33 }
  34
  35 int sha1close(struct sha1file *f, unsigned char *result, unsigned int flags)
  36 {
  37         int fd;
  38         unsigned offset = f->offset;
  39
  40         if (offset) {
  41                 SHA1_Update(&f->ctx, f->buffer, offset);
  42                 sha1flush(f, offset);
  43                 f->offset = 0;
  44         }
  45         SHA1_Final(f->buffer, &f->ctx);
  46         if (result)
  47                 hashcpy(result, f->buffer);
  48         if (flags & (CSUM_CLOSE | CSUM_FSYNC)) {
  49                 /* write checksum and close fd */
  50                 sha1flush(f, 20);
  51                 if (flags & CSUM_FSYNC)
  52                         fsync_or_die(f->fd, f->name);
  53                 if (close(f->fd))
  54                         die("%s: sha1 file error on close (%s)",
  55                             f->name, strerror(errno));
  56                 fd = 0;
  57         } else
  58                 fd = f->fd;
  59         free(f);
  60         return fd;
  61 }
  62
  63 int sha1write(struct sha1file *f, void *buf, unsigned int count)
  64 {
  65         if (f->do_crc)
  66                 f->crc32 = crc32(f->crc32, buf, count);
  67         while (count) {
  68                 unsigned offset = f->offset;
  69                 unsigned left = sizeof(f->buffer) - offset;
  70                 unsigned nr = count > left ? left : count;
  71
  72                 memcpy(f->buffer + offset, buf, nr);
  73                 count -= nr;
  74                 offset += nr;
  75                 buf = (char *) buf + nr;
  76                 left -= nr;
  77                 if (!left) {
  78                         SHA1_Update(&f->ctx, f->buffer, offset);
  79                         sha1flush(f, offset);
  80                         offset = 0;
  81                 }
  82                 f->offset = offset;
  83         }
  84         return 0;
  85 }
  86
  87 struct sha1file *sha1fd(int fd, const char *name)
  88 {
  89         return sha1fd_throughput(fd, name, NULL);
  90 }
  91
  92 struct sha1file *sha1fd_throughput(int fd, const char *name, struct progress *tp)
  93 {
  94         struct sha1file *f = xmalloc(sizeof(*f));
  95         f->fd = fd;
  96         f->offset = 0;
  97         f->total = 0;
  98         f->tp = tp;
  99         f->name = name;
 100         f->do_crc = 0;
 101         SHA1_Init(&f->ctx);
 102         return f;
 103 }
 104
 105 void crc32_begin(struct sha1file *f)
 106 {
 107         f->crc32 = crc32(0, Z_NULL, 0);
 108         f->do_crc = 1;
 109 }
 110
 111 uint32_t crc32_end(struct sha1file *f)
 112 {
 113         f->do_crc = 0;
 114         return f->crc32;
 115 }