Andrew's git - gitweb.git/blob

   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
  13static 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 write error. Out of diskspace");
  28                if (errno == EAGAIN || errno == EINTR)
  29                        continue;
  30                die("sha1 file write error (%s)", strerror(errno));
  31        }
  32}
  33
  34int sha1close(struct sha1file *f)
  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        sha1flush(f, 20);
  43        return 0;
  44}
  45
  46int sha1write(struct sha1file *f, void *buf, unsigned int count)
  47{
  48        while (count) {
  49                unsigned offset = f->offset;
  50                unsigned left = sizeof(f->buffer) - offset;
  51                unsigned nr = count > left ? left : count;
  52
  53                memcpy(f->buffer + offset, buf, nr);
  54                count -= nr;
  55                offset += nr;
  56                left -= nr;
  57                if (!left) {
  58                        SHA1_Update(&f->ctx, f->buffer, offset);
  59                        sha1flush(f, offset);
  60                        offset = 0;
  61                }
  62                f->offset = offset;
  63        }
  64        return 0;
  65}
  66
  67struct sha1file *sha1create(const char *fmt, ...)
  68{
  69        static char filename[PATH_MAX];
  70        struct sha1file *f;
  71        unsigned len;
  72        va_list arg;
  73        int fd;
  74
  75        va_start(arg, fmt);
  76        len = vsnprintf(filename, PATH_MAX, fmt, arg);
  77        va_end(arg);
  78
  79        if (len >= PATH_MAX)
  80                die("you wascally wabbit, you");
  81        fd = open(filename, O_CREAT | O_EXCL | O_WRONLY, 0644);
  82        if (fd < 0)
  83                die("unable to open %s (%s)", filename, strerror(errno));
  84        f = xmalloc(sizeof(*f));
  85        f->fd = fd;
  86        f->error = 0;
  87        f->offset = 0;
  88        SHA1_Init(&f->ctx);
  89        return f;
  90}
  91
  92int sha1write_compressed(struct sha1file *f, void *in, unsigned int size)
  93{
  94        z_stream stream;
  95        unsigned long maxsize;
  96        void *out;
  97
  98        memset(&stream, 0, sizeof(stream));
  99        deflateInit(&stream, Z_DEFAULT_COMPRESSION);
 100        maxsize = deflateBound(&stream, size);
 101        out = xmalloc(maxsize);
 102
 103        /* Compress it */
 104        stream.next_in = in;
 105        stream.avail_in = size;
 106
 107        stream.next_out = out;
 108        stream.avail_out = maxsize;
 109
 110        while (deflate(&stream, Z_FINISH) == Z_OK)
 111                /* nothing */;
 112        deflateEnd(&stream);
 113
 114        size = stream.total_out;
 115        sha1write(f, out, size);
 116        free(out);
 117        return size;
 118}
 119
 120