xref: /third_party/eudev/src/shared/fileio.c

/***
  This file is part of eudev, forked from systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <unistd.h>
#include <sys/sendfile.h>
#include "fileio.h"
#include "util.h"
#include "strv.h"
#include "utf8.h"
#include "ctype.h"

int write_string_stream(FILE *f, const char *line) {
        assert(f);
        assert(line);

        errno = 0;

        fputs(line, f);
        if (!endswith(line, "\n"))
                fputc('\n', f);

        fflush(f);

        if (ferror(f))
                return errno ? -errno : -EIO;

        return 0;
}

int write_string_file(const char *fn, const char *line) {
        _cleanup_fclose_ FILE *f = NULL;

        assert(fn);
        assert(line);

        f = fopen(fn, "we");
        if (!f)
                return -errno;

        return write_string_stream(f, line);
}
int read_one_line_file(const char *fn, char **line) {
        _cleanup_fclose_ FILE *f = NULL;
        char t[LINE_MAX], *c;

        assert(fn);
        assert(line);

        f = fopen(fn, "re");
        if (!f)
                return -errno;

        if (!fgets(t, sizeof(t), f)) {

                if (ferror(f))
                        return errno ? -errno : -EIO;

                t[0] = 0;
        }

        c = strdup(t);
        if (!c)
                return -ENOMEM;
        truncate_nl(c);

        *line = c;
        return 0;
}

int read_full_stream(FILE *f, char **contents, size_t *size) {
        size_t n, l;
        _cleanup_free_ char *buf = NULL;
        struct stat st;

        assert(f);
        assert(contents);

        if (fstat(fileno(f), &st) < 0)
                return -errno;

        n = LINE_MAX;

        if (S_ISREG(st.st_mode)) {

                /* Safety check */
                if (st.st_size > 4*1024*1024)
                        return -E2BIG;

                /* Start with the right file size, but be prepared for
                 * files from /proc which generally report a file size
                 * of 0 */
                if (st.st_size > 0)
                        n = st.st_size;
        }

        l = 0;
        for (;;) {
                char *t;
                size_t k;

                t = realloc(buf, n+1);
                if (!t)
                        return -ENOMEM;

                buf = t;
                k = fread(buf + l, 1, n - l, f);

                if (k <= 0) {
                        if (ferror(f))
                                return -errno;

                        break;
                }

                l += k;
                n *= 2;

                /* Safety check */
                if (n > 4*1024*1024)
                        return -E2BIG;
        }

        buf[l] = 0;
        *contents = buf;
        buf = NULL; /* do not free */

        if (size)
                *size = l;

        return 0;
}

int read_full_file(const char *fn, char **contents, size_t *size) {
        _cleanup_fclose_ FILE *f = NULL;

        assert(fn);
        assert(contents);

        f = fopen(fn, "re");
        if (!f)
                return -errno;

        return read_full_stream(f, contents, size);
}