diff options
Diffstat (limited to 'src/fold.c')
| -rw-r--r-- | src/fold.c | 307 |
1 files changed, 307 insertions, 0 deletions
diff --git a/src/fold.c b/src/fold.c new file mode 100644 index 0000000..5c0428d --- /dev/null +++ b/src/fold.c @@ -0,0 +1,307 @@ +/* fold -- wrap each input line to fit in specified width. + Copyright (C) 1991-2023 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 3 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. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + +/* Written by David MacKenzie, djm@gnu.ai.mit.edu. */ + +#include <config.h> + +#include <stdio.h> +#include <getopt.h> +#include <sys/types.h> + +#include "system.h" +#include "fadvise.h" +#include "xdectoint.h" + +#define TAB_WIDTH 8 + +/* The official name of this program (e.g., no 'g' prefix). */ +#define PROGRAM_NAME "fold" + +#define AUTHORS proper_name ("David MacKenzie") + +/* If nonzero, try to break on whitespace. */ +static bool break_spaces; + +/* If nonzero, count bytes, not column positions. */ +static bool count_bytes; + +/* If nonzero, at least one of the files we read was standard input. */ +static bool have_read_stdin; + +static char const shortopts[] = "bsw:0::1::2::3::4::5::6::7::8::9::"; + +static struct option const longopts[] = +{ + {"bytes", no_argument, nullptr, 'b'}, + {"spaces", no_argument, nullptr, 's'}, + {"width", required_argument, nullptr, 'w'}, + {GETOPT_HELP_OPTION_DECL}, + {GETOPT_VERSION_OPTION_DECL}, + {nullptr, 0, nullptr, 0} +}; + +void +usage (int status) +{ + if (status != EXIT_SUCCESS) + emit_try_help (); + else + { + printf (_("\ +Usage: %s [OPTION]... [FILE]...\n\ +"), + program_name); + fputs (_("\ +Wrap input lines in each FILE, writing to standard output.\n\ +"), stdout); + + emit_stdin_note (); + emit_mandatory_arg_note (); + + fputs (_("\ + -b, --bytes count bytes rather than columns\n\ + -s, --spaces break at spaces\n\ + -w, --width=WIDTH use WIDTH columns instead of 80\n\ +"), stdout); + fputs (HELP_OPTION_DESCRIPTION, stdout); + fputs (VERSION_OPTION_DESCRIPTION, stdout); + emit_ancillary_info (PROGRAM_NAME); + } + exit (status); +} + +/* Assuming the current column is COLUMN, return the column that + printing C will move the cursor to. + The first column is 0. */ + +static size_t +adjust_column (size_t column, char c) +{ + if (!count_bytes) + { + if (c == '\b') + { + if (column > 0) + column--; + } + else if (c == '\r') + column = 0; + else if (c == '\t') + column += TAB_WIDTH - column % TAB_WIDTH; + else /* if (isprint (c)) */ + column++; + } + else + column++; + return column; +} + +/* Fold file FILENAME, or standard input if FILENAME is "-", + to stdout, with maximum line length WIDTH. + Return true if successful. */ + +static bool +fold_file (char const *filename, size_t width) +{ + FILE *istream; + int c; + size_t column = 0; /* Screen column where next char will go. */ + size_t offset_out = 0; /* Index in 'line_out' for next char. */ + static char *line_out = nullptr; + static size_t allocated_out = 0; + int saved_errno; + + if (STREQ (filename, "-")) + { + istream = stdin; + have_read_stdin = true; + } + else + istream = fopen (filename, "r"); + + if (istream == nullptr) + { + error (0, errno, "%s", quotef (filename)); + return false; + } + + fadvise (istream, FADVISE_SEQUENTIAL); + + while ((c = getc (istream)) != EOF) + { + if (offset_out + 1 >= allocated_out) + line_out = X2REALLOC (line_out, &allocated_out); + + if (c == '\n') + { + line_out[offset_out++] = c; + fwrite (line_out, sizeof (char), offset_out, stdout); + column = offset_out = 0; + continue; + } + + rescan: + column = adjust_column (column, c); + + if (column > width) + { + /* This character would make the line too long. + Print the line plus a newline, and make this character + start the next line. */ + if (break_spaces) + { + bool found_blank = false; + size_t logical_end = offset_out; + + /* Look for the last blank. */ + while (logical_end) + { + --logical_end; + if (isblank (to_uchar (line_out[logical_end]))) + { + found_blank = true; + break; + } + } + + if (found_blank) + { + size_t i; + + /* Found a blank. Don't output the part after it. */ + logical_end++; + fwrite (line_out, sizeof (char), (size_t) logical_end, + stdout); + putchar ('\n'); + /* Move the remainder to the beginning of the next line. + The areas being copied here might overlap. */ + memmove (line_out, line_out + logical_end, + offset_out - logical_end); + offset_out -= logical_end; + for (column = i = 0; i < offset_out; i++) + column = adjust_column (column, line_out[i]); + goto rescan; + } + } + + if (offset_out == 0) + { + line_out[offset_out++] = c; + continue; + } + + line_out[offset_out++] = '\n'; + fwrite (line_out, sizeof (char), (size_t) offset_out, stdout); + column = offset_out = 0; + goto rescan; + } + + line_out[offset_out++] = c; + } + + saved_errno = errno; + if (!ferror (istream)) + saved_errno = 0; + + if (offset_out) + fwrite (line_out, sizeof (char), (size_t) offset_out, stdout); + + if (STREQ (filename, "-")) + clearerr (istream); + else if (fclose (istream) != 0 && !saved_errno) + saved_errno = errno; + + if (saved_errno) + { + error (0, saved_errno, "%s", quotef (filename)); + return false; + } + + return true; +} + +int +main (int argc, char **argv) +{ + size_t width = 80; + int i; + int optc; + bool ok; + + initialize_main (&argc, &argv); + set_program_name (argv[0]); + setlocale (LC_ALL, ""); + bindtextdomain (PACKAGE, LOCALEDIR); + textdomain (PACKAGE); + + atexit (close_stdout); + + break_spaces = count_bytes = have_read_stdin = false; + + while ((optc = getopt_long (argc, argv, shortopts, longopts, nullptr)) != -1) + { + char optargbuf[2]; + + switch (optc) + { + case 'b': /* Count bytes rather than columns. */ + count_bytes = true; + break; + + case 's': /* Break at word boundaries. */ + break_spaces = true; + break; + + case '0': case '1': case '2': case '3': case '4': + case '5': case '6': case '7': case '8': case '9': + if (optarg) + optarg--; + else + { + optargbuf[0] = optc; + optargbuf[1] = '\0'; + optarg = optargbuf; + } + FALLTHROUGH; + case 'w': /* Line width. */ + width = xdectoumax (optarg, 1, SIZE_MAX - TAB_WIDTH - 1, "", + _("invalid number of columns"), 0); + break; + + case_GETOPT_HELP_CHAR; + + case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS); + + default: + usage (EXIT_FAILURE); + } + } + + if (argc == optind) + ok = fold_file ("-", width); + else + { + ok = true; + for (i = optind; i < argc; i++) + ok &= fold_file (argv[i], width); + } + + if (have_read_stdin && fclose (stdin) == EOF) + error (EXIT_FAILURE, errno, "-"); + + return ok ? EXIT_SUCCESS : EXIT_FAILURE; +} |