X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fgetndelim2.c;h=fcdf7df2d071047c58df2d3df31eff9aa9b8cca7;hb=1b94e030d122eb05acd5054b711e7bf6d49994e3;hp=be34e40e6104b35324e98549645ca36bb98d48d7;hpb=032b1ce80ba621afc4f241570e0ae6716a59ce60;p=gnulib.git diff --git a/lib/getndelim2.c b/lib/getndelim2.c index be34e40e6..fcdf7df2d 100644 --- a/lib/getndelim2.c +++ b/lib/getndelim2.c @@ -1,7 +1,7 @@ /* getndelim2 - Read a line from a stream, stopping at one of 2 delimiters, with bounded memory allocation. - Copyright (C) 1993, 1996, 1997, 1998, 2000, 2003, 2004, 2006, 2008 Free + Copyright (C) 1993, 1996-1998, 2000, 2003-2004, 2006, 2008-2011 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify @@ -51,6 +51,13 @@ # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2)) #endif +/* Use this to suppress gcc's `...may be used before initialized' warnings. */ +#ifdef lint +# define IF_LINT(Code) Code +#else +# define IF_LINT(Code) /* empty */ +#endif + /* The maximum value that getndelim2 can return without suffering from overflow problems, either internally (because of pointer subtraction overflow) or due to the API (because of ssize_t). */ @@ -64,19 +71,19 @@ ssize_t getndelim2 (char **lineptr, size_t *linesize, size_t offset, size_t nmax, int delim1, int delim2, FILE *stream) { - size_t nbytes_avail; /* Allocated but unused bytes in *LINEPTR. */ - char *read_pos; /* Where we're reading into *LINEPTR. */ + size_t nbytes_avail; /* Allocated but unused bytes in *LINEPTR. */ + char *read_pos; /* Where we're reading into *LINEPTR. */ ssize_t bytes_stored = -1; char *ptr = *lineptr; size_t size = *linesize; - bool done = false; + bool found_delimiter; if (!ptr) { size = nmax < MIN_CHUNK ? nmax : MIN_CHUNK; ptr = malloc (size); if (!ptr) - return -1; + return -1; } if (size < offset) @@ -96,89 +103,103 @@ getndelim2 (char **lineptr, size_t *linesize, size_t offset, size_t nmax, flockfile (stream); - while (!done) + found_delimiter = false; + do { - /* Here always ptr + size == read_pos + nbytes_avail. */ + /* Here always ptr + size == read_pos + nbytes_avail. + Also nbytes_avail > 0 || size < nmax. */ - int c; + int c IF_LINT (= 0); const char *buffer; size_t buffer_len; buffer = freadptr (stream, &buffer_len); if (buffer) - { - if (delim1 != EOF) - { - const char *end = memchr2 (buffer, delim1, delim2, buffer_len); - if (end) - { - buffer_len = end - buffer + 1; - done = true; - } - } - } + { + if (delim1 != EOF) + { + const char *end = memchr2 (buffer, delim1, delim2, buffer_len); + if (end) + { + buffer_len = end - buffer + 1; + found_delimiter = true; + } + } + } else - { - c = getc (stream); - if (c == EOF) - { - /* Return partial line, if any. */ - if (read_pos == ptr) - goto unlock_done; - else - break; - } - if (c == delim1 || c == delim2) - done = true; - buffer_len = 1; - } + { + c = getc (stream); + if (c == EOF) + { + /* Return partial line, if any. */ + if (read_pos == ptr) + goto unlock_done; + else + break; + } + if (c == delim1 || c == delim2) + found_delimiter = true; + buffer_len = 1; + } /* We always want at least one byte left in the buffer, since we - always (unless we get an error while reading the first byte) - NUL-terminate the line buffer. */ - - if (nbytes_avail < 1 + buffer_len && size < nmax) - { - size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size; - char *newptr; - - if (newsize < buffer_len) - newsize = buffer_len + size; - if (! (size < newsize && newsize <= nmax)) - newsize = nmax; - - if (GETNDELIM2_MAXIMUM < newsize - offset) - { - size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1; - if (size == newsizemax) - goto unlock_done; - newsize = newsizemax; - } - - nbytes_avail = newsize - (read_pos - ptr); - newptr = realloc (ptr, newsize); - if (!newptr) - goto unlock_done; - ptr = newptr; - size = newsize; - read_pos = size - nbytes_avail + ptr; - } + always (unless we get an error while reading the first byte) + NUL-terminate the line buffer. */ + + if (nbytes_avail < buffer_len + 1 && size < nmax) + { + /* Grow size proportionally, not linearly, to avoid O(n^2) + running time. */ + size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size; + char *newptr; + + /* Increase newsize so that it becomes + >= (read_pos - ptr) + buffer_len. */ + if (newsize - (read_pos - ptr) < buffer_len + 1) + newsize = (read_pos - ptr) + buffer_len + 1; + /* Respect nmax. This handles possible integer overflow. */ + if (! (size < newsize && newsize <= nmax)) + newsize = nmax; + + if (GETNDELIM2_MAXIMUM < newsize - offset) + { + size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1; + if (size == newsizemax) + goto unlock_done; + newsize = newsizemax; + } + + nbytes_avail = newsize - (read_pos - ptr); + newptr = realloc (ptr, newsize); + if (!newptr) + goto unlock_done; + ptr = newptr; + size = newsize; + read_pos = size - nbytes_avail + ptr; + } + + /* Here, if size < nmax, nbytes_avail >= buffer_len + 1. + If size == nmax, nbytes_avail > 0. */ if (1 < nbytes_avail) - { - size_t copy_len = nbytes_avail - 1; - if (buffer_len < copy_len) - copy_len = buffer_len; - if (buffer) - memcpy (read_pos, buffer, copy_len); - else - *read_pos = c; - read_pos += copy_len; - nbytes_avail -= copy_len; - } + { + size_t copy_len = nbytes_avail - 1; + if (buffer_len < copy_len) + copy_len = buffer_len; + if (buffer) + memcpy (read_pos, buffer, copy_len); + else + *read_pos = c; + read_pos += copy_len; + nbytes_avail -= copy_len; + } + + /* Here still nbytes_avail > 0. */ + if (buffer && freadseek (stream, buffer_len)) - goto unlock_done; + goto unlock_done; } + while (!found_delimiter); /* Done - NUL terminate and return the number of bytes read. At this point we know that nbytes_avail >= 1. */