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getline c实现

时间:2017-01-17 12:40:36      阅读:438      评论:0      收藏:0      [点我收藏+]

标签:hunk   under   ifd   copy   eof   pre   register   rom   caller   

Linux的实现在toolchain里边,所以这里直接copy苹果的实现,这样对于内存分配处理就清楚了。
/* getline.c -- Replacement for GNU C library function getline Copyright (C) 1993 Free Software Foundation, Inc. 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; either version 2 of the License, or (at your option) any later version. 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. */ /* Written by Jan Brittenson, bson@gnu.ai.mit.edu. */ #ifdef HAVE_CONFIG_H #include <config.h> #endif #include <sys/types.h> #include <stdio.h> #include <assert.h> #include <errno.h> #if STDC_HEADERS #include <stdlib.h> #else char *malloc (), *realloc (); #endif /* Always add at least this many bytes when extending the buffer. */ #define MIN_CHUNK 64 /* Read up to (and including) a TERMINATOR from STREAM into *LINEPTR + OFFSET (and null-terminate it). *LINEPTR is a pointer returned from malloc (or NULL), pointing to *N characters of space. It is realloc‘d as necessary. Return the number of characters read (not including the null terminator), or -1 on error or EOF. On a -1 return, the caller should check feof(), if not then errno has been set to indicate the error. */ int getstr (lineptr, n, stream, terminator, offset) char **lineptr; size_t *n; FILE *stream; char terminator; int offset; { int nchars_avail; /* Allocated but unused chars in *LINEPTR. */ char *read_pos; /* Where we‘re reading into *LINEPTR. */ int ret; if (!lineptr || !n || !stream) { errno = EINVAL; return -1; } if (!*lineptr) { *n = MIN_CHUNK; *lineptr = malloc (*n); if (!*lineptr) { errno = ENOMEM; return -1; } } nchars_avail = *n - offset; read_pos = *lineptr + offset; for (;;) { int save_errno; register int c = getc (stream); save_errno = errno; /* We always want at least one char left in the buffer, since we always (unless we get an error while reading the first char) NUL-terminate the line buffer. */ assert((*lineptr + *n) == (read_pos + nchars_avail)); if (nchars_avail < 2) { if (*n > MIN_CHUNK) *n *= 2; else *n += MIN_CHUNK; nchars_avail = *n + *lineptr - read_pos; *lineptr = realloc (*lineptr, *n); if (!*lineptr) { errno = ENOMEM; return -1; } read_pos = *n - nchars_avail + *lineptr; assert((*lineptr + *n) == (read_pos + nchars_avail)); } if (ferror (stream)) { /* Might like to return partial line, but there is no place for us to store errno. And we don‘t want to just lose errno. */ errno = save_errno; return -1; } if (c == EOF) { /* Return partial line, if any. */ if (read_pos == *lineptr) return -1; else break; } *read_pos++ = c; nchars_avail--; if (c == terminator) /* Return the line. */ break; } /* Done - NUL terminate and return the number of chars read. */ *read_pos = ‘\0‘; ret = read_pos - (*lineptr + offset); return ret; } int getline (lineptr, n, stream) char **lineptr; size_t *n; FILE *stream; { return getstr (lineptr, n, stream, ‘\n‘, 0); }
 

getline c实现

标签:hunk   under   ifd   copy   eof   pre   register   rom   caller   

原文地址:http://www.cnblogs.com/brightmind/p/6292426.html

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