minix/commands/grep/grep.c
2010-05-12 16:28:54 +00:00

379 lines
9.4 KiB
C

/* grep - search a file for a pattern Author: Norbert Schlenker */
/* Norbert Schlenker (nfs@princeton.edu) 1990-02-08
* Released into the public domain.
*
* Grep searches files for lines containing a pattern, as specified by
* a regular expression, and prints those lines. It is invoked by:
* grep [flags] [pattern] [file ...]
*
* Flags:
* -e pattern useful when pattern begins with '-'
* -c print a count of lines matched
* -i ignore case
* -l prints just file names, no lines (quietly overrides -n)
* -n printed lines are preceded by relative line numbers
* -s prints errors only (quietly overrides -l and -n)
* -v prints lines which don't contain the pattern
*
* Semantic note:
* If both -l and -v are specified, grep prints the names of those
* files which do not contain the pattern *anywhere*.
*
* Exit:
* Grep sets an exit status which can be tested by the caller.
* Note that these settings are not necessarily compatible with
* any other version of grep, especially when -v is specified.
* Possible status values are:
* 0 if any matches are found
* 1 if no matches are found
* 2 if syntax errors are detected or any file cannot be opened
*/
/* External interfaces */
#include <sys/types.h>
#include <regexp.h> /* Thanks to Henry Spencer */
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
/* Internal constants */
#define MATCH 0 /* exit code: some match somewhere */
#define NO_MATCH 1 /* exit code: no match on any line */
#define FAILURE 2 /* exit code: syntax error or bad file name */
/* Macros */
#define SET_FLAG(c) (flags[(c)-'a'] = 1)
#define FLAG(c) (flags[(c)-'a'] != 0)
#define uppercase(c) (((unsigned) ((c) - 'A')) <= ('Z' - 'A'))
#define downcase(c) ((c) - 'A' + 'a')
/* Private storage */
static char *program; /* program name */
static char flags[26]; /* invocation flags */
static regexp *expression; /* compiled search pattern */
static const char *rerr; /* error message */
/* External variables. */
extern int optind;
extern char *optarg;
/* Internal interfaces */
_PROTOTYPE(int main, (int argc, char **argv));
_PROTOTYPE(static int match, (FILE *input, char *label, char *filename));
_PROTOTYPE(static char *get_line, (FILE *input));
_PROTOTYPE(static char *map_nocase, (char *line));
_PROTOTYPE(void regerror , (const char *s ) );
_PROTOTYPE(static void tov8, (char *v8pattern, char *pattern));
int main(argc, argv)
int argc;
char *argv[];
{
int opt; /* option letter from getopt() */
int egrep=0; /* using extended regexp operators */
char *pattern; /* search pattern */
char *v8pattern; /* v8 regexp search pattern */
int exit_status = NO_MATCH; /* exit status for our caller */
int file_status; /* status of search in one file */
FILE *input; /* input file (if not stdin) */
program = argv[0];
if (strlen(program)>=5 && strcmp(program+strlen(program)-5,"egrep")==0) egrep=1;
memset(flags, 0, sizeof(flags));
pattern = NULL;
/* Process any command line flags. */
while ((opt = getopt(argc, argv, "e:cilnsv")) != EOF) {
if (opt == '?')
exit_status = FAILURE;
else
if (opt == 'e')
pattern = optarg;
else
SET_FLAG(opt);
}
/* Detect a few problems. */
if ((exit_status == FAILURE) || (optind == argc && pattern == NULL)) {
fprintf(stderr,"Usage: %s [-cilnsv] [-e] expression [file ...]\n",program);
exit(FAILURE);
}
/* Ensure we have a usable pattern. */
if (pattern == NULL)
pattern = argv[optind++];
/* Map pattern to lowercase if -i given. */
if (FLAG('i')) {
char *p;
for (p = pattern; *p != '\0'; p++) {
if (uppercase(*p))
*p = downcase(*p);
}
}
if (!egrep) {
if ((v8pattern=malloc(2*strlen(pattern)))==(char*)0) {
fprintf(stderr,"%s: out of memory\n");
exit(FAILURE);
}
tov8(v8pattern,pattern);
} else v8pattern=pattern;
rerr=(char*)0;
if ((expression = regcomp(v8pattern)) == NULL) {
fprintf(stderr,"%s: bad regular expression",program);
if (rerr) fprintf(stderr," (%s)",rerr);
fprintf(stderr,"\n");
exit(FAILURE);
}
/* Process the files appropriately. */
if (optind == argc) { /* no file names - find pattern in stdin */
exit_status = match(stdin, (char *) NULL, "<stdin>");
}
else
if (optind + 1 == argc) { /* one file name - find pattern in it */
if (strcmp(argv[optind], "-") == 0) {
exit_status = match(stdin, (char *) NULL, "-");
} else {
if ((input = fopen(argv[optind], "r")) == NULL) {
fprintf(stderr, "%s: couldn't open %s\n",
program, argv[optind]);
exit_status = FAILURE;
}
else {
exit_status = match(input, (char *) NULL, argv[optind]);
}
}
}
else
while (optind < argc) { /* lots of file names - find pattern in all */
if (strcmp(argv[optind], "-") == 0) {
file_status = match(stdin, "-", "-");
} else {
if ((input = fopen(argv[optind], "r")) == NULL) {
fprintf(stderr, "%s: couldn't open %s\n",
program, argv[optind]);
exit_status = FAILURE;
} else {
file_status = match(input, argv[optind], argv[optind]);
fclose(input);
}
}
if (exit_status != FAILURE)
exit_status &= file_status;
++optind;
}
return(exit_status);
}
/* match - matches the lines of a file with the regular expression.
* To improve performance when either -s or -l is specified, this
* function handles those cases specially.
*/
static int match(input, label, filename)
FILE *input;
char *label;
char *filename;
{
char *line, *testline; /* pointers to input line */
long int lineno = 0; /* line number */
long int matchcount = 0; /* lines matched */
int status = NO_MATCH; /* summary of what was found in this file */
if (FLAG('s') || FLAG('l')) {
while ((line = get_line(input)) != NULL) {
testline = FLAG('i') ? map_nocase(line) : line;
if (regexec(expression, testline, 1)) {
status = MATCH;
break;
}
}
if (FLAG('l'))
if ((!FLAG('v') && status == MATCH) ||
( FLAG('v') && status == NO_MATCH))
puts(filename);
return status;
}
while ((line = get_line(input)) != NULL) {
++lineno;
testline = FLAG('i') ? map_nocase(line) : line;
if (regexec(expression, testline, 1)) {
status = MATCH;
if (!FLAG('v')) {
if (label != NULL)
printf("%s:", label);
if (FLAG('n'))
printf("%ld:", lineno);
if (!FLAG('c')) puts(line);
matchcount++;
}
} else {
if (FLAG('v')) {
if (label != NULL)
printf("%s:", label);
if (FLAG('n'))
printf("%ld:", lineno);
if (!FLAG('c')) puts(line);
matchcount++;
}
}
}
if (FLAG('c')) printf("%ld\n", matchcount);
return status;
}
/* get_line - fetch a line from the input file
* This function reads a line from the input file into a dynamically
* allocated buffer. If the line is too long for the current buffer,
* attempts will be made to increase its size to accomodate the line.
* The trailing newline is stripped before returning to the caller.
*/
#define FIRST_BUFFER (size_t)256 /* first buffer size */
static char *buf = NULL; /* input buffer */
static size_t buf_size = 0; /* input buffer size */
static char *get_line(input)
FILE *input;
{
int n;
register char *bp;
register int c;
char *new_buf;
size_t new_size;
if (buf_size == 0) {
if ((buf = (char *) malloc(FIRST_BUFFER)) == NULL) {
fprintf(stderr,"%s: not enough memory\n",program);
exit(FAILURE);
}
buf_size = FIRST_BUFFER;
}
bp = buf;
n = buf_size;
while (1) {
while (--n > 0 && (c = getc(input)) != EOF) {
if (c == '\n') {
*bp = '\0';
return buf;
}
*bp++ = c;
}
if (c == EOF)
return (ferror(input) || bp == buf) ? NULL : buf;
new_size = buf_size << 1;
if ((new_buf = (char *) realloc(buf, new_size)) == NULL) {
fprintf(stderr, "%s: line too long - truncated\n", program);
while ((c = getc(input)) != EOF && c != '\n') ;
*bp = '\0';
return buf;
} else {
bp = new_buf + (buf_size - 1);
n = buf_size + 1;
buf = new_buf;
buf_size = new_size;
}
}
}
/* map_nocase - map a line down to lowercase letters only.
* bad points: assumes line gotten from get_line.
* there is more than A-Z you say?
*/
static char *map_nocase(line)
char *line;
{
static char *mapped=(char*)0;
static size_t map_size = 0;
char *mp;
if (map_size < buf_size) {
if ((mapped=realloc(mapped,map_size=buf_size)) == NULL) {
fprintf(stderr,"%s: not enough memory\n",program);
exit(FAILURE);
}
}
mp = mapped;
do {
*mp++ = uppercase(*line) ? downcase(*line) : *line;
} while (*line++ != '\0');
return mapped;
}
/* In basic regular expressions, the characters ?, +, |, (, and )
are taken literally; use the backslashed versions for RE operators.
In v8 regular expressions, things are the other way round, so
we have to swap those characters and their backslashed versions.
*/
static void tov8(char *v8, char *basic)
{
while (*basic) switch (*basic)
{
case '?':
case '+':
case '|':
case '(':
case ')':
{
*v8++='\\';
*v8++=*basic++;
break;
}
case '\\':
{
switch (*(basic+1))
{
case '?':
case '+':
case '|':
case '(':
case ')':
{
*v8++=*++basic;
++basic;
break;
}
case '\0':
{
*v8++=*basic++;
break;
}
default:
{
*v8++=*basic++;
*v8++=*basic++;
}
}
break;
}
default:
{
*v8++=*basic++;
}
}
*v8++='\0';
}
/* Regular expression code calls this routine to print errors. */
void regerror(s)
const char *s;
{
rerr=s;
}