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                         display_throughput(f->tp, ret);
  22                         buf = (char *) buf + ret;
  23                         count -= ret;
  24                         if (count)
  25                                 continue;
  26                         return;
  27                 }
  28                 if (!ret)
  29                         die("sha1 file '%s' write error. Out of diskspace", f->name);
  30                 die("sha1 file '%s' write error (%s)", f->name, strerror(errno));
  31         }
  32 }
  33
  34 int sha1close(struct sha1file *f, unsigned char *result, int final)
  35 {
  36         int fd;
  37         unsigned offset = f->offset;
  38         if (offset) {
  39                 SHA1_Update(&f->ctx, f->buffer, offset);
  40                 sha1flush(f, offset);
  41                 f->offset = 0;
  42         }
  43         if (final) {
  44                 /* write checksum and close fd */
  45                 SHA1_Final(f->buffer, &f->ctx);
  46                 if (result)
  47                         hashcpy(result, f->buffer);
  48                 sha1flush(f, 20);
  49                 if (close(f->fd))
  50                         die("%s: sha1 file error on close (%s)",
  51                             f->name, strerror(errno));
  52                 fd = 0;
  53         } else
  54                 fd = f->fd;
  55         free(f);
  56         return fd;
  57 }
  58
  59 int sha1write(struct sha1file *f, void *buf, unsigned int count)
  60 {
  61         if (f->do_crc)
  62                 f->crc32 = crc32(f->crc32, buf, count);
  63         while (count) {
  64                 unsigned offset = f->offset;
  65                 unsigned left = sizeof(f->buffer) - offset;
  66                 unsigned nr = count > left ? left : count;
  67
  68                 memcpy(f->buffer + offset, buf, nr);
  69                 count -= nr;
  70                 offset += nr;
  71                 buf = (char *) buf + nr;
  72                 left -= nr;
  73                 if (!left) {
  74                         SHA1_Update(&f->ctx, f->buffer, offset);
  75                         sha1flush(f, offset);
  76                         offset = 0;
  77                 }
  78                 f->offset = offset;
  79         }
  80         return 0;
  81 }
  82
  83 struct sha1file *sha1fd(int fd, const char *name)
  84 {
  85         return sha1fd_throughput(fd, name, NULL);
  86 }
  87
  88 struct sha1file *sha1fd_throughput(int fd, const char *name, struct progress *tp)
  89 {
  90         struct sha1file *f;
  91         unsigned len;
  92
  93         f = xmalloc(sizeof(*f));
  94
  95         len = strlen(name);
  96         if (len >= PATH_MAX)
  97                 die("you wascally wabbit, you");
  98         f->namelen = len;
  99         memcpy(f->name, name, len+1);
 100
 101         f->fd = fd;
 102         f->error = 0;
 103         f->offset = 0;
 104         f->tp = tp;
 105         f->do_crc = 0;
 106         SHA1_Init(&f->ctx);
 107         return f;
 108 }
 109
 110 void crc32_begin(struct sha1file *f)
 111 {
 112         f->crc32 = crc32(0, Z_NULL, 0);
 113         f->do_crc = 1;
 114 }
 115
 116 uint32_t crc32_end(struct sha1file *f)
 117 {
 118         f->do_crc = 0;
 119         return f->crc32;
 120 }