[Toybox] [patch] add grep

[Strake]

# HG changeset patch
# User Strake
# Date 1373245375 18000
# Node ID 29e47cf402a5f81640c4b0a0e38d5f7741bc7ad6
# Parent  f8db1f6ec4ab6972ee05126aae860e6ea104360e
add grep

diff -r f8db1f6ec4ab -r 29e47cf402a5 toys/posix/grep.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toys/posix/grep.c	Sun Jul 07 20:02:55 2013 -0500
@@ -0,0 +1,100 @@
+/* grep.c - print lines what match given regular expression
+ *
+ * Copyright 2013 CE Strake <strake888 at gmail.com>
+ *
+ * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/
+ * See http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/cmdbehav.html
+
+USE_GREP(NEWTOY(grep, "Einvclq", TOYFLAG_BIN))
+
+config GREP
+  bool "grep"
+  default y
+  help
+    usage: grep [-clq] [-Einv] RE [file...]
+
+    modes:
+      default:	print lines from each file what match regular expression RE.
+      -c:	print the number of matching lines in each file.
+      -l:	print all matching file names.
+      -q:	print nil; quit with code 0 when match found.
+
+    flags:
+      -E:	extended RE syntax
+      -i:	case insensitive
+      -n:	print line numbers
+      -v:	invert match
+*/
+
+#define FOR_grep
+#include "toys.h"
+#include <regex.h>
+#include <err.h>
+
+/* could be in GLOBALS but so need initialization code */
+char mode = 0;
+int c = 1;
+
+regex_t re; /* fails in GLOBALS */
+
+static void do_grep (int fd, char *name) {
+  int n = 0, nMatch = 0;
+  size_t l;
+  char *x;
+  FILE *f;
+
+  f = fdopen (fd, "r");
+  if (!f) err (2, "failed to open %s", name);
+
+  x = 0;
+  for (;;) {
+    if (getline (&x, &l, f) < 0) {
+      if (feof (f)) break;
+      err (2, "failed to read");
+    }
+    n++; /* start at 1 */
+
+    if (regexec (&re, x, 0, 0, 0) == 0) {
+      c = 0; nMatch++;
+      switch (mode) {
+      case 'q':
+        exit (0);
+      case 'l':
+        printf ("%s\n", name);
+        goto end;
+      case 'c':
+        break;
+      default:
+        printf ("%s:", name);
+        if (toys.optflags & FLAG_n) printf ("%d:", n);
+        fputs (x, stdout);
+      }
+    }
+  }
+
+  if (mode == 'c') printf ("%s:%d\n", name, nMatch);
+
+end:
+  free (x);
+  fclose (f);
+}
+
+void grep_main (void) {
+  if (toys.optc < 1) errx (2, "no RE");
+
+  if (regcomp (&re, toys.optargs[0],
+               REG_NOSUB |
+               (toys.optflags & FLAG_E ? REG_EXTENDED : 0) |
+               (toys.optflags & FLAG_i ? REG_ICASE    : 0)) != 0) {
+    errx (2, "bad RE");
+  }
+
+  if (toys.optflags & FLAG_c) mode = 'c';
+  if (toys.optflags & FLAG_l) mode = 'l';
+  if (toys.optflags & FLAG_q) mode = 'q';
+
+  if (toys.optc > 1) loopfiles (toys.optargs + 1, do_grep);
+  else do_grep (0, "-");
+
+  exit (c);
+}

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