cosmopolitan/libc/x/xslurp.c

73 lines
3.1 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/struct/stat.h"
#include "libc/errno.h"
#include "libc/mem/mem.h"
#include "libc/runtime/runtime.h"
#include "libc/sysv/consts/madv.h"
#include "libc/sysv/consts/o.h"
/**
* Reads entire file into memory.
*
* @return NUL-terminated malloc'd contents, or NULL w/ errno
* @note this is uninterruptible
*/
char *xslurp(const char *path, size_t *opt_out_size) {
int fd;
ssize_t rc;
size_t i, got;
char *res, *p;
struct stat st;
res = NULL;
if ((fd = open(path, O_RDONLY)) != -1) {
if (fstat(fd, &st) != -1 && (res = valloc(st.st_size))) {
if (st.st_size > 2 * 1024 * 1024) {
fadvise(fd, 0, st.st_size, MADV_SEQUENTIAL);
}
for (i = 0; i < st.st_size; i += got) {
TryAgain:
if ((rc = pread(fd, res + i, st.st_size - i, i)) != -1) {
if (!(got = rc)) {
if (fstat(fd, &st) == -1) {
abort();
}
}
} else if (errno == EINTR) {
goto TryAgain;
} else {
free(res);
res = NULL;
break;
}
}
if (res) {
if (opt_out_size) {
*opt_out_size = st.st_size;
}
res[i] = '\0';
}
}
close(fd);
}
return res;
}