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 '%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
  34int 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        return 0;
  49}
  50
  51int sha1write(struct sha1file *f, void *buf, unsigned int count)
  52{
  53        while (count) {
  54                unsigned offset = f->offset;
  55                unsigned left = sizeof(f->buffer) - offset;
  56                unsigned nr = count > left ? left : count;
  57
  58                memcpy(f->buffer + offset, buf, nr);
  59                count -= nr;
  60                offset += nr;
  61                buf += nr;
  62                left -= nr;
  63                if (!left) {
  64                        SHA1_Update(&f->ctx, f->buffer, offset);
  65                        sha1flush(f, offset);
  66                        offset = 0;
  67                }
  68                f->offset = offset;
  69        }
  70        return 0;
  71}
  72
  73struct sha1file *sha1create(const char *fmt, ...)
  74{
  75        struct sha1file *f;
  76        unsigned len;
  77        va_list arg;
  78        int fd;
  79
  80        f = xmalloc(sizeof(*f));
  81
  82        va_start(arg, fmt);
  83        len = vsnprintf(f->name, sizeof(f->name), fmt, arg);
  84        va_end(arg);
  85        if (len >= PATH_MAX)
  86                die("you wascally wabbit, you");
  87        f->namelen = len;
  88
  89        fd = open(f->name, O_CREAT | O_EXCL | O_WRONLY, 0644);
  90        if (fd < 0)
  91                die("unable to open %s (%s)", f->name, strerror(errno));
  92        f->fd = fd;
  93        f->error = 0;
  94        f->offset = 0;
  95        SHA1_Init(&f->ctx);
  96        return f;
  97}
  98
  99int sha1write_compressed(struct sha1file *f, void *in, unsigned int size)
 100{
 101        z_stream stream;
 102        unsigned long maxsize;
 103        void *out;
 104
 105        memset(&stream, 0, sizeof(stream));
 106        deflateInit(&stream, Z_DEFAULT_COMPRESSION);
 107        maxsize = deflateBound(&stream, size);
 108        out = xmalloc(maxsize);
 109
 110        /* Compress it */
 111        stream.next_in = in;
 112        stream.avail_in = size;
 113
 114        stream.next_out = out;
 115        stream.avail_out = maxsize;
 116
 117        while (deflate(&stream, Z_FINISH) == Z_OK)
 118                /* nothing */;
 119        deflateEnd(&stream);
 120
 121        size = stream.total_out;
 122        sha1write(f, out, size);
 123        free(out);
 124        return size;
 125}
 126
 127