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/*
* Copyright 2019 Intel Corporation
* SPDX-License-Identifier: MIT
*/
#include "os_file.h"
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/stat.h>
#if defined(WIN32)
#include <io.h>
#define open _open
#define fdopen _fdopen
#define O_CREAT _O_CREAT
#define O_EXCL _O_EXCL
#define O_WRONLY _O_WRONLY
#endif
FILE *
os_file_create_unique(const char *filename, int filemode)
{
int fd = open(filename, O_CREAT | O_EXCL | O_WRONLY, filemode);
if (fd == -1)
return NULL;
return fdopen(fd, "w");
}
#if defined(__linux__)
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <unistd.h>
/* copied from <linux/kcmp.h> */
#define KCMP_FILE 0
static ssize_t
readN(int fd, char *buf, size_t len)
{
int err = -ENODATA;
size_t total = 0;
do {
ssize_t ret = read(fd, buf + total, len - total);
if (ret < 0)
ret = -errno;
if (ret == -EINTR || ret == -EAGAIN)
continue;
if (ret <= 0) {
err = ret;
break;
}
total += ret;
} while (total != len);
return total ? (ssize_t)total : err;
}
char *
os_read_file(const char *filename)
{
/* Note that this also serves as a slight margin to avoid a 2x grow when
* the file is just a few bytes larger when we read it than when we
* fstat'ed it.
* The string's NULL terminator is also included in here.
*/
size_t len = 64;
int fd = open(filename, O_RDONLY);
if (fd == -1) {
/* errno set by open() */
return NULL;
}
/* Pre-allocate a buffer at least the size of the file if we can read
* that information.
*/
struct stat stat;
if (fstat(fd, &stat) == 0)
len += stat.st_size;
char *buf = malloc(len);
if (!buf) {
close(fd);
errno = -ENOMEM;
return NULL;
}
ssize_t actually_read;
size_t offset = 0, remaining = len - 1;
while ((actually_read = readN(fd, buf + offset, remaining)) == (ssize_t)remaining) {
char *newbuf = realloc(buf, 2 * len);
if (!newbuf) {
free(buf);
close(fd);
errno = -ENOMEM;
return NULL;
}
buf = newbuf;
len *= 2;
offset += actually_read;
remaining = len - offset - 1;
}
close(fd);
if (actually_read > 0)
offset += actually_read;
/* Final resize to actual size */
len = offset + 1;
char *newbuf = realloc(buf, len);
if (!newbuf) {
free(buf);
errno = -ENOMEM;
return NULL;
}
buf = newbuf;
buf[offset] = '\0';
return buf;
}
bool
os_same_file_description(int fd1, int fd2)
{
pid_t pid = getpid();
return syscall(SYS_kcmp, pid, pid, KCMP_FILE, fd1, fd2) == 0;
}
#else
#include "u_debug.h"
char *
os_read_file(const char *filename)
{
errno = -ENOSYS;
return NULL;
}
bool
os_same_file_description(int fd1, int fd2)
{
if (fd1 == fd2)
return true;
debug_warn_once("Can't tell if different file descriptors reference the same"
" file description, false negatives might cause trouble!\n");
return false;
}
#endif
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