source: MondoRescue/branches/2.2.9/mindi-busybox/libbb/get_line_from_file.c@ 3320

/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) 2005, 2006 Rob Landley <rob@landley.net>
 * Copyright (C) 2004 Erik Andersen <andersen@codepoet.org>
 * Copyright (C) 2001 Matt Krai
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

#include "libbb.h"

/* This function reads an entire line from a text file, up to a newline
 * or NUL byte, inclusive.  It returns a malloc'ed char * which
 * must be free'ed by the caller.  If end is NULL '\n' isn't considered
 * end of line.  If end isn't NULL, length of the chunk is stored in it.
 * If lineno is not NULL, *lineno is incremented for each line,
 * and also trailing '\' is recognized as line continuation.
 *
 * Returns NULL if EOF/error. */
char* FAST_FUNC bb_get_chunk_with_continuation(FILE *file, int *end, int *lineno)
{
    int ch;
    int idx = 0;
    char *linebuf = NULL;
    int linebufsz = 0;

    while ((ch = getc(file)) != EOF) {
        /* grow the line buffer as necessary */
        if (idx >= linebufsz) {
            linebufsz += 256;
            linebuf = xrealloc(linebuf, linebufsz);
        }
        linebuf[idx++] = (char) ch;
        if (!ch)
            break;
        if (end && ch == '\n') {
            if (lineno == NULL)
                break;
            (*lineno)++;
            if (idx < 2 || linebuf[idx-2] != '\\')
                break;
            idx -= 2;
        }
    }
    if (end)
        *end = idx;
    if (linebuf) {
        // huh, does fgets discard prior data on error like this?
        // I don't think so....
        //if (ferror(file)) {
        //  free(linebuf);
        //  return NULL;
        //}
        linebuf = xrealloc(linebuf, idx + 1);
        linebuf[idx] = '\0';
    }
    return linebuf;
}

char* FAST_FUNC bb_get_chunk_from_file(FILE *file, int *end)
{
    return bb_get_chunk_with_continuation(file, end, NULL);
}

/* Get line, including trailing \n if any */
char* FAST_FUNC xmalloc_fgets(FILE *file)
{
    int i;

    return bb_get_chunk_from_file(file, &i);
}
/* Get line.  Remove trailing \n */
char* FAST_FUNC xmalloc_fgetline(FILE *file)
{
    int i;
    char *c = bb_get_chunk_from_file(file, &i);

    if (i && c[--i] == '\n')
        c[i] = '\0';

    return c;
}

#if 0
/* GNUism getline() should be faster (not tested) than a loop with fgetc */

/* Get line, including trailing \n if any */
char* FAST_FUNC xmalloc_fgets(FILE *file)
{
    char *res_buf = NULL;
    size_t res_sz;

    if (getline(&res_buf, &res_sz, file) == -1) {
        free(res_buf); /* uclibc allocates a buffer even on EOF. WTF? */
        res_buf = NULL;
    }
//TODO: trimming to res_sz?
    return res_buf;
}
/* Get line.  Remove trailing \n */
char* FAST_FUNC xmalloc_fgetline(FILE *file)
{
    char *res_buf = NULL;
    size_t res_sz;

    res_sz = getline(&res_buf, &res_sz, file);

    if ((ssize_t)res_sz != -1) {
        if (res_buf[res_sz - 1] == '\n')
            res_buf[--res_sz] = '\0';
//TODO: trimming to res_sz?
    } else {
        free(res_buf); /* uclibc allocates a buffer even on EOF. WTF? */
        res_buf = NULL;
    }
    return res_buf;
}

#endif

#if 0
/* Faster routines (~twice as fast). +170 bytes. Unused as of 2008-07.
 *
 * NB: they stop at NUL byte too.
 * Performance is important here. Think "grep 50gigabyte_file"...
 * Ironically, grep can't use it because of NUL issue.
 * We sorely need C lib to provide fgets which reports size!
 *
 * Update:
 * Actually, uclibc and glibc have it. man getline. It's GNUism,
 *   but very useful one (if it's as fast as this code).
 * TODO:
 * - currently, sed and sort use bb_get_chunk_from_file and heavily
 *   depend on its "stop on \n or \0" behavior, and STILL they fail
 *   to handle all cases with embedded NULs correctly. So:
 * - audit sed and sort; convert them to getline FIRST.
 * - THEN ditch bb_get_chunk_from_file, replace it with getline.
 * - provide getline implementation for non-GNU systems.
 */

static char* xmalloc_fgets_internal(FILE *file, int *sizep)
{
    int len;
    int idx = 0;
    char *linebuf = NULL;

    while (1) {
        char *r;

        linebuf = xrealloc(linebuf, idx + 0x100);
        r = fgets(&linebuf[idx], 0x100, file);
        if (!r) {
            /* need to terminate in case this is error
             * (EOF puts NUL itself) */
            linebuf[idx] = '\0';
            break;
        }
        /* stupid. fgets knows the len, it should report it somehow */
        len = strlen(&linebuf[idx]);
        idx += len;
        if (len != 0xff || linebuf[idx - 1] == '\n')
            break;
    }
    *sizep = idx;
    if (idx) {
        /* xrealloc(linebuf, idx + 1) is up to caller */
        return linebuf;
    }
    free(linebuf);
    return NULL;
}

/* Get line, remove trailing \n */
char* FAST_FUNC xmalloc_fgetline_fast(FILE *file)
{
    int sz;
    char *r = xmalloc_fgets_internal(file, &sz);
    if (r && r[sz - 1] == '\n')
        r[--sz] = '\0';
    return r; /* not xrealloc(r, sz + 1)! */
}

char* FAST_FUNC xmalloc_fgets(FILE *file)
{
    int sz;
    return xmalloc_fgets_internal(file, &sz);
}

/* Get line, remove trailing \n */
char* FAST_FUNC xmalloc_fgetline(FILE *file)
{
    int sz;
    char *r = xmalloc_fgets_internal(file, &sz);
    if (!r)
        return r;
    if (r[sz - 1] == '\n')
        r[--sz] = '\0';
    return xrealloc(r, sz + 1);
}
#endif