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, int final)
  36 {
  37         int fd;
  38         unsigned offset = f->offset;
  39         if (offset) {
  40                 SHA1_Update(&f->ctx, f->buffer, offset);
  41                 sha1flush(f, offset);
  42                 f->offset = 0;
  43         }
  44         if (final) {
  45                 /* write checksum and close fd */
  46                 SHA1_Final(f->buffer, &f->ctx);
  47                 if (result)
  48                         hashcpy(result, f->buffer);
  49                 sha1flush(f, 20);
  50                 if (close(f->fd))
  51                         die("%s: sha1 file error on close (%s)",
  52                             f->name, strerror(errno));
  53                 fd = 0;
  54         } else
  55                 fd = f->fd;
  56         free(f);
  57         return fd;
  58 }
  59
  60 int sha1write(struct sha1file *f, void *buf, unsigned int count)
  61 {
  62         if (f->do_crc)
  63                 f->crc32 = crc32(f->crc32, buf, count);
  64         while (count) {
  65                 unsigned offset = f->offset;
  66                 unsigned left = sizeof(f->buffer) - offset;
  67                 unsigned nr = count > left ? left : count;
  68
  69                 memcpy(f->buffer + offset, buf, nr);
  70                 count -= nr;
  71                 offset += nr;
  72                 buf = (char *) buf + nr;
  73                 left -= nr;
  74                 if (!left) {
  75                         SHA1_Update(&f->ctx, f->buffer, offset);
  76                         sha1flush(f, offset);
  77                         offset = 0;
  78                 }
  79                 f->offset = offset;
  80         }
  81         return 0;
  82 }
  83
  84 struct sha1file *sha1fd(int fd, const char *name)
  85 {
  86         return sha1fd_throughput(fd, name, NULL);
  87 }
  88
  89 struct sha1file *sha1fd_throughput(int fd, const char *name, struct progress *tp)
  90 {
  91         struct sha1file *f;
  92         unsigned len;
  93
  94         f = xmalloc(sizeof(*f));
  95
  96         len = strlen(name);
  97         if (len >= PATH_MAX)
  98                 die("you wascally wabbit, you");
  99         f->namelen = len;
 100         memcpy(f->name, name, len+1);
 101
 102         f->fd = fd;
 103         f->error = 0;
 104         f->offset = 0;
 105         f->total = 0;
 106         f->tp = tp;
 107         f->do_crc = 0;
 108         SHA1_Init(&f->ctx);
 109         return f;
 110 }
 111
 112 void crc32_begin(struct sha1file *f)
 113 {
 114         f->crc32 = crc32(0, Z_NULL, 0);
 115         f->do_crc = 1;
 116 }
 117
 118 uint32_t crc32_end(struct sha1file *f)
 119 {
 120         f->do_crc = 0;
 121         return f->crc32;
 122 }