86 lines
2.3 KiB
C
86 lines
2.3 KiB
C
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/*-------------------------------------------------------------------------
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*
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* pg_get_line.c
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* fgets() with an expansible result buffer
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*
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* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* src/common/pg_get_line.c
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef FRONTEND
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#include "postgres.h"
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#else
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#include "postgres_fe.h"
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#endif
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#include "common/string.h"
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#include "lib/stringinfo.h"
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/*
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* pg_get_line()
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*
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* This is meant to be equivalent to fgets(), except that instead of
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* reading into a caller-supplied, fixed-size buffer, it reads into
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* a palloc'd (in frontend, really malloc'd) string, which is resized
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* as needed to handle indefinitely long input lines. The caller is
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* responsible for pfree'ing the result string when appropriate.
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*
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* As with fgets(), returns NULL if there is a read error or if no
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* characters are available before EOF. The caller can distinguish
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* these cases by checking ferror(stream).
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*
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* Since this is meant to be equivalent to fgets(), the trailing newline
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* (if any) is not stripped. Callers may wish to apply pg_strip_crlf().
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*
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* Note that while I/O errors are reflected back to the caller to be
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* dealt with, an OOM condition for the palloc'd buffer will not be;
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* there'll be an ereport(ERROR) or exit(1) inside stringinfo.c.
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*/
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char *
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pg_get_line(FILE *stream)
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{
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StringInfoData buf;
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initStringInfo(&buf);
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/* Read some data, appending it to whatever we already have */
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while (fgets(buf.data + buf.len, buf.maxlen - buf.len, stream) != NULL)
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{
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buf.len += strlen(buf.data + buf.len);
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/* Done if we have collected a newline */
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if (buf.len > 0 && buf.data[buf.len - 1] == '\n')
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return buf.data;
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/* Make some more room in the buffer, and loop to read more data */
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enlargeStringInfo(&buf, 128);
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}
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/* Did fgets() fail because of an I/O error? */
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if (ferror(stream))
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{
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/* ensure that free() doesn't mess up errno */
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int save_errno = errno;
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pfree(buf.data);
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errno = save_errno;
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return NULL;
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}
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/* If we read no data before reaching EOF, we should return NULL */
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if (buf.len == 0)
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{
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pfree(buf.data);
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return NULL;
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}
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/* No newline at EOF ... so return what we have */
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return buf.data;
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}
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