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/* zio.c (simulation of non-standard low-level i/o functions) */
/* Written by Andrew Makhorin <mao@gnu.org>, April 2011
* For conditions of distribution and use, see copyright notice in
* zlib.h */
/* (reserved for copyright notice) */
#include <assert.h>
#include <stdio.h>
#include "zio.h"
static FILE *file[FOPEN_MAX];
static int initialized = 0;
static void initialize(void)
{ int fd;
assert(!initialized);
file[0] = stdin;
file[1] = stdout;
file[2] = stderr;
for (fd = 3; fd < FOPEN_MAX; fd++)
file[fd] = NULL;
initialized = 1;
return;
}
int open(const char *path, int oflag, ...)
{ FILE *fp;
int fd;
if (!initialized) initialize();
/* see file gzlib.c, function gz_open */
if (oflag == O_RDONLY)
fp = fopen(path, "rb");
else if (oflag == (O_WRONLY | O_CREAT | O_TRUNC))
fp = fopen(path, "wb");
else if (oflag == (O_WRONLY | O_CREAT | O_APPEND))
fp = fopen(path, "ab");
else
assert(oflag != oflag);
if (fp == NULL)
return -1;
for (fd = 0; fd < FOPEN_MAX; fd++)
if (file[fd] == NULL) break;
assert(fd < FOPEN_MAX);
file[fd] = fp;
return fd;
}
long read(int fd, void *buf, unsigned long nbyte)
{ unsigned long count;
if (!initialized) initialize();
assert(0 <= fd && fd < FOPEN_MAX);
assert(file[fd] != NULL);
count = fread(buf, 1, nbyte, file[fd]);
if (ferror(file[fd]))
return -1;
return count;
}
long write(int fd, const void *buf, unsigned long nbyte)
{ unsigned long count;
if (!initialized) initialize();
assert(0 <= fd && fd < FOPEN_MAX);
assert(file[fd] != NULL);
count = fwrite(buf, 1, nbyte, file[fd]);
if (count != nbyte)
return -1;
if (fflush(file[fd]) != 0)
return -1;
return count;
}
long lseek(int fd, long offset, int whence)
{ if (!initialized) initialize();
assert(0 <= fd && fd < FOPEN_MAX);
assert(file[fd] != NULL);
if (fseek(file[fd], offset, whence) != 0)
return -1;
return ftell(file[fd]);
}
int close(int fd)
{ if (!initialized) initialize();
assert(0 <= fd && fd < FOPEN_MAX);
assert(file[fd] != NULL);
fclose(file[fd]);
file[fd] = NULL;
return 0;
}
/* eof */
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