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 int sha1flush(struct sha1file *f, unsigned int count)
  14 {
  15         void *buf = f->buffer;
  16
  17         for (;;) {
  18                 int ret = write(f->fd, buf, count);
  19                 if (ret > 0) {
  20                         buf += ret;
  21                         count -= ret;
  22                         if (count)
  23                                 continue;
  24                         return 0;
  25                 }
  26                 if (!ret)
  27                         die("sha1 file '%s' write error. Out of diskspace", f->name);
  28                 if (errno == EAGAIN || errno == EINTR)
  29                         continue;
  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 update)
  35 {
  36         unsigned offset = f->offset;
  37         if (offset) {
  38                 SHA1_Update(&f->ctx, f->buffer, offset);
  39                 sha1flush(f, offset);
  40         }
  41         SHA1_Final(f->buffer, &f->ctx);
  42         if (result)
  43                 memcpy(result, f->buffer, 20);
  44         if (update)
  45                 sha1flush(f, 20);
  46         if (close(f->fd))
  47                 die("%s: sha1 file error on close (%s)", f->name, strerror(errno));
  48         free(f);
  49         return 0;
  50 }
  51
  52 int sha1write(struct sha1file *f, void *buf, unsigned int count)
  53 {
  54         while (count) {
  55                 unsigned offset = f->offset;
  56                 unsigned left = sizeof(f->buffer) - offset;
  57                 unsigned nr = count > left ? left : count;
  58
  59                 memcpy(f->buffer + offset, buf, nr);
  60                 count -= nr;
  61                 offset += nr;
  62                 buf += nr;
  63                 left -= nr;
  64                 if (!left) {
  65                         SHA1_Update(&f->ctx, f->buffer, offset);
  66                         sha1flush(f, offset);
  67                         offset = 0;
  68                 }
  69                 f->offset = offset;
  70         }
  71         return 0;
  72 }
  73
  74 struct sha1file *sha1create(const char *fmt, ...)
  75 {
  76         struct sha1file *f;
  77         unsigned len;
  78         va_list arg;
  79         int fd;
  80
  81         f = xmalloc(sizeof(*f));
  82
  83         va_start(arg, fmt);
  84         len = vsnprintf(f->name, sizeof(f->name), fmt, arg);
  85         va_end(arg);
  86         if (len >= PATH_MAX)
  87                 die("you wascally wabbit, you");
  88         f->namelen = len;
  89
  90         fd = open(f->name, O_CREAT | O_EXCL | O_WRONLY, 0666);
  91         if (fd < 0)
  92                 die("unable to open %s (%s)", f->name, strerror(errno));
  93         f->fd = fd;
  94         f->error = 0;
  95         f->offset = 0;
  96         SHA1_Init(&f->ctx);
  97         return f;
  98 }
  99
 100 struct sha1file *sha1fd(int fd, const char *name)
 101 {
 102         struct sha1file *f;
 103         unsigned len;
 104
 105         f = xmalloc(sizeof(*f));
 106
 107         len = strlen(name);
 108         if (len >= PATH_MAX)
 109                 die("you wascally wabbit, you");
 110         f->namelen = len;
 111         memcpy(f->name, name, len+1);
 112
 113         f->fd = fd;
 114         f->error = 0;
 115         f->offset = 0;
 116         SHA1_Init(&f->ctx);
 117         return f;
 118 }
 119
 120 int sha1write_compressed(struct sha1file *f, void *in, unsigned int size)
 121 {
 122         z_stream stream;
 123         unsigned long maxsize;
 124         void *out;
 125
 126         memset(&stream, 0, sizeof(stream));
 127         deflateInit(&stream, Z_DEFAULT_COMPRESSION);
 128         maxsize = deflateBound(&stream, size);
 129         out = xmalloc(maxsize);
 130
 131         /* Compress it */
 132         stream.next_in = in;
 133         stream.avail_in = size;
 134
 135         stream.next_out = out;
 136         stream.avail_out = maxsize;
 137
 138         while (deflate(&stream, Z_FINISH) == Z_OK)
 139                 /* nothing */;
 140         deflateEnd(&stream);
 141
 142         size = stream.total_out;
 143         sha1write(f, out, size);
 144         free(out);
 145         return size;
 146 }
 147
 148