100 lines
2.8 KiB
C
100 lines
2.8 KiB
C
/* Read a line from an nss_files database file.
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Copyright (C) 2020-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <nss_files.h>
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#include <ctype.h>
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#include <errno.h>
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#include <string.h>
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int
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__nss_readline (FILE *fp, char *buf, size_t len, off64_t *poffset)
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{
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/* We need space for at least one character, the line terminator,
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and the NUL byte. */
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if (len < 3)
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{
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*poffset = -1;
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__set_errno (ERANGE);
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return ERANGE;
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}
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while (true)
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{
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/* Keep original offset for retries. */
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*poffset = __ftello64 (fp);
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buf[len - 1] = '\xff'; /* Marker to recognize truncation. */
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if (__fgets_unlocked (buf, len, fp) == NULL)
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{
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if (__feof_unlocked (fp))
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{
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__set_errno (ENOENT);
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return ENOENT;
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}
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else
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{
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/* Any other error. Do not return ERANGE in this case
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because the caller would retry. */
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if (errno == ERANGE)
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__set_errno (EINVAL);
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return errno;
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}
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}
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else if (buf[len - 1] != '\xff')
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/* The buffer is too small. Arrange for re-reading the same
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line on the next call. */
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return __nss_readline_seek (fp, *poffset);
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/* __fgets_unlocked succeeded. */
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/* Remove leading whitespace. */
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char *p = buf;
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while (isspace (*p))
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++p;
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if (*p == '\0' || *p == '#')
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/* Skip empty lines and comments. */
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continue;
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if (p != buf)
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memmove (buf, p, strlen (p));
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/* Return line to the caller. */
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return 0;
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}
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}
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libc_hidden_def (__nss_readline)
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int
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__nss_readline_seek (FILE *fp, off64_t offset)
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{
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if (offset < 0 /* __ftello64 failed. */
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|| __fseeko64 (fp, offset, SEEK_SET) < 0)
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{
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/* Without seeking support, it is not possible to
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re-read the same line, so this is a hard failure. */
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fseterr_unlocked (fp);
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__set_errno (ESPIPE);
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return ESPIPE;
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}
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else
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{
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__set_errno (ERANGE);
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return ERANGE;
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}
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}
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