Implemented -A, -B, and -C flags with BB_FEATURE_GREP_CONTEXT option set.

1 files changed, 125 insertions, 14 deletions

diff --git a/findutils/grep.c b/findutils/grep.c
index ce2990f64..3eea7792f 100644
--- a/findutils/grep.c
+++ b/findutils/grep.c
@@ -28,10 +28,10 @@
 #include <errno.h>
 #include "busybox.h"
 
-extern void xregcomp(regex_t *preg, const char *regex, int cflags);
 
 extern int optind; /* in unistd.h */
 extern int errno;  /* for use with strerror() */
+extern void xregcomp(regex_t *preg, const char *regex, int cflags); /* in busybox.h */
 
 /* options */
 static int ignore_case       = 0;
@@ -42,11 +42,34 @@ static int be_quiet          = 0;
 static int invert_search     = 0;
 static int suppress_err_msgs = 0;
 
-/* globals */
+#ifdef BB_FEATURE_GREP_CONTEXT
+extern char *optarg; /* in getopt.h */
+static int lines_before      = 0;
+static int lines_after       = 0;
+static char **before_buf     = NULL;
+static int last_line_printed = 0;
+#endif /* BB_FEATURE_GREP_CONTEXT */
+
+/* globals used internally */
 static regex_t regex; /* storage space for compiled regular expression */
 static int matched; /* keeps track of whether we ever matched */
 static char *cur_file = NULL; /* the current file we are reading */
 
+static void print_line(const char *line, int linenum, char decoration)
+{
+#ifdef BB_FEATURE_GREP_CONTEXT
+        /* possibly print the little '--' seperator */
+        if (last_line_printed && last_line_printed < linenum - 1) {
+                puts("--");
+        }
+        last_line_printed = linenum;
+#endif
+        if (print_filename)
+                printf("%s%c", cur_file, decoration);
+        if (print_line_num)
+                printf("%i%c", linenum, decoration);
+        puts(line);
+}
 
 static void grep_file(FILE *file)
 {
@@ -54,15 +77,23 @@ static void grep_file(FILE *file)
         int ret;
         int linenum = 0;
         int nmatches = 0;
+#ifdef BB_FEATURE_GREP_CONTEXT
+        int print_n_lines_after = 0;
+        int curpos = 0; /* track where we are in the circular 'before' buffer */
+        int idx = 0; /* used for iteration through the circular buffer */
+#endif /* BB_FEATURE_GREP_CONTEXT */ 
 
         while ((line = get_line_from_file(file)) != NULL) {
                 chomp(line);
                 linenum++;
-                ret = regexec(&regex, line, 0, NULL, 0);
 
-                /* test for a postitive-assertion match (regexec returned success (0)
+                /*
+                 * test for a postitive-assertion match (regexec returns success (0)
                  * and the user did not specify invert search), or a negative-assertion
-                 * match (vice versa) */
+                 * match (regexec returns failure (REG_NOMATCH) and the user specified
+                 * invert search)
+                 */
+                ret = regexec(&regex, line, 0, NULL, 0);
                 if ((ret == 0 && !invert_search) || (ret == REG_NOMATCH && invert_search)) {
 
                         /* if we found a match but were told to be quiet, stop here and
@@ -72,17 +103,62 @@ static void grep_file(FILE *file)
                                 exit(0);
                         }
 
-                        /* otherwise, keep track of matches, print the matched line, and
-                         * whatever else the user wanted */
+                        /* otherwise, keep track of matches and print the matched line */
                         nmatches++;
                         if (!print_count_only) {
-                                if (print_filename)
-                                        printf("%s:", cur_file);
-                                if (print_line_num)
-                                        printf("%i:", linenum);
-                                puts(line);
+#ifdef BB_FEATURE_GREP_CONTEXT
+                                int prevpos = (curpos == 0) ? lines_before - 1 : curpos - 1;
+
+                                /* if we were told to print 'before' lines and there is at least
+                                 * one line in the circular buffer, print them */
+                                if (lines_before && before_buf[prevpos] != NULL)
+                                {
+                                        int first_buf_entry_line_num = linenum - lines_before;
+
+                                        /* advance to the first entry in the circular buffer, and
+                                         * figure out the line number is of the first line in the
+                                         * buffer */
+                                        idx = curpos;
+                                        while (before_buf[idx] == NULL) {
+                                                idx = (idx + 1) % lines_before;
+                                                first_buf_entry_line_num++;
+                                        }
+
+                                        /* now print each line in the buffer, clearing them as we go */
+                                        while (before_buf[idx] != NULL) {
+                                                print_line(before_buf[idx], first_buf_entry_line_num, '-');
+                                                free(before_buf[idx]);
+                                                before_buf[idx] = NULL;
+                                                idx = (idx + 1) % lines_before;
+                                                first_buf_entry_line_num++;
+                                        }
+
+                                }
+
+                                /* make a note that we need to print 'after' lines */
+                                print_n_lines_after = lines_after;
+#endif /* BB_FEATURE_GREP_CONTEXT */ 
+                                print_line(line, linenum, ':');
+                        }
+                }
+#ifdef BB_FEATURE_GREP_CONTEXT
+                else { /* no match */
+                        /* Add the line to the circular 'before' buffer */
+                        if(lines_before)
+                        {
+                                if(before_buf[curpos])
+                                        free(before_buf[curpos]);
+                                before_buf[curpos] = strdup(line);
+                                curpos = (curpos + 1) % lines_before;
                         }
                 }
+
+                /* if we need to print some context lines after the last match, do so */
+                if (print_n_lines_after && (last_line_printed != linenum)) {
+                        print_line(line, linenum, '-');
+                        print_n_lines_after--;
+                }
+#endif /* BB_FEATURE_GREP_CONTEXT */ 
                 free(line);
         }
 
@@ -93,7 +169,7 @@ static void grep_file(FILE *file)
                 printf("%i\n", nmatches);
         }
 
-        /* record if we matched */
+        /* remember if we matched */
         if (nmatches != 0)
                 matched = 1;
 }
@@ -102,9 +178,16 @@ extern int grep_main(int argc, char **argv)
 {
         int opt;
         int reflags;
+#ifdef BB_FEATURE_GREP_CONTEXT
+        char *junk;
+#endif
 
         /* do normal option parsing */
-        while ((opt = getopt(argc, argv, "iHhnqvsc")) > 0) {
+        while ((opt = getopt(argc, argv, "iHhnqvsc"
+#ifdef BB_FEATURE_GREP_CONTEXT
+"A:B:C:"
+#endif
+)) > 0) {
                 switch (opt) {
                         case 'i':
                                 ignore_case++;
@@ -130,6 +213,25 @@ extern int grep_main(int argc, char **argv)
                         case 'c':
                                 print_count_only++;
                                 break;
+#ifdef BB_FEATURE_GREP_CONTEXT
+                        case 'A':
+                                lines_after = strtoul(optarg, &junk, 10);
+                                if(*junk != '\0')
+                                        error_msg_and_die("invalid context length argument");
+                                break;
+                        case 'B':
+                                lines_before = strtoul(optarg, &junk, 10);
+                                if(*junk != '\0')
+                                        error_msg_and_die("invalid context length argument");
+                                before_buf = (char **)calloc(lines_before, sizeof(char *));
+                                break;
+                        case 'C':
+                                lines_after = lines_before = strtoul(optarg, &junk, 10);
+                                if(*junk != '\0')
+                                        error_msg_and_die("invalid context length argument");
+                                before_buf = (char **)calloc(lines_before, sizeof(char *));
+                                break;
+#endif /* BB_FEATURE_GREP_CONTEXT */
                 }
         }
 
@@ -137,6 +239,15 @@ extern int grep_main(int argc, char **argv)
         if (argv[optind] == NULL)
                 usage(grep_usage);
 
+        /* sanity check */
+        if (print_count_only || be_quiet) {
+                print_line_num = 0;
+#ifdef BB_FEATURE_GREP_CONTEXT
+                lines_before = 0;
+                lines_after = 0;
+#endif
+        }
+
         /* compile the regular expression
          * we're not going to mess with sub-expressions, and we need to
          * treat newlines right. */