add directory study

study/linux-travel/MINIX-1.5/1.5/Source/commands/look.c

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+/*  look - look up words in the dictionary	Author: Terrence W. Holm */
+
+
+/*  look  [ -f ]  prefix[/suffix]  [ dictionary ]
+ *
+ *  Looks for all words in the on-line dictionary
+ *  beginning with the specified <prefix> and ending
+ *  with <suffix>.
+ *
+ *  Fold to lower case if "-f" given. Use the file
+ *  "dictionary" or /usr/lib/dictionary.
+ *
+ ******************************************************
+ *
+ *  This command was written for MINIX, and is slightly
+ *  different than the UNIX look(1). First of all, the
+ *  list of words is in a different place. Second, these
+ *  words are not sorted by -df. And finally, the
+ *  ``suffix'' option was added to limit the output of
+ *  the multiple variations of each word as contained
+ *  in the MINIX dictionary.
+ */
+
+#include <ctype.h>
+#include <sys/types.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdio.h>
+
+#ifdef UNIX
+#define  WORDS   "/usr/dict/words"
+#else
+#define  WORDS   "/usr/lib/dictionary"
+#endif
+
+#define  MAX_WORD_LENGTH   80	/* including '\0'  */
+
+
+main(argc, argv)
+int argc;
+char *argv[];
+
+{
+  int fold = 0;
+  char *prefix;
+  char *suffix;
+  char *word_file = WORDS;
+
+  FILE *words;
+  long head = 0;
+  long tail;
+  long mid_point;
+  char word[MAX_WORD_LENGTH];
+  char unfolded_word[MAX_WORD_LENGTH];
+  int cmp;
+
+
+  /* Check the arguments: fold, prefix, suffix and word_file.  */
+
+  if (argc > 1 && strcmp(argv[1], "-f") == 0) {
+	fold = 1;
+	--argc;
+	++argv;
+  }
+  if (argc < 2 || argc > 3) {
+	fprintf(stderr, "Usage: %s [-f] prefix[/suffix] [dictionary]\n", argv[0]);
+	exit(1);
+  }
+  prefix = argv[1];
+
+  if ((suffix = strchr(prefix, '/')) == NULL)
+	suffix = "";
+  else
+	*suffix++ = '\0';
+
+  if (fold) {
+	Fold(prefix);
+	Fold(suffix);
+  }
+  if (argc == 3) word_file = argv[2];
+
+
+  /* Open the word file, and find how big it is.  */
+  if ((words = fopen(word_file, "r")) == NULL) File_Error(word_file);
+  if (fseek(words, 0L, SEEK_END) != 0) File_Error(word_file);
+  tail = ftell(words);
+
+  /* Use a binary search on the word file to find a 512 byte	 */
+  /* Window containing the first word starting with "prefix".	 */
+  while (head + 512 < tail) {
+	mid_point = (head + tail) / 2;
+	if (fseek(words, mid_point, SEEK_SET) != 0) File_Error(word_file);
+
+	/* Skip the partial word we seeked into.  */
+	fgets(word, MAX_WORD_LENGTH, words);
+	if (fgets(word, MAX_WORD_LENGTH, words) == NULL)
+		File_Error(word_file);
+	word[strlen(word) - 1] = '\0';	/* remove \n  */
+	strcpy(unfolded_word, word);
+	if (fold) Fold(word);
+	cmp = strcmp(prefix, word);
+	if (cmp == 0) {
+		printf("%s\n", unfolded_word);
+		head = ftell(words);
+		break;
+	}
+	if (cmp < 0)
+		tail = mid_point;
+	else
+		head = ftell(words);
+  }
+
+  fseek(words, head, SEEK_SET);
+
+
+
+  {
+	/* Print out all the words starting with "prefix".  */
+
+	int prefix_length = strlen(prefix);
+	int suffix_length = strlen(suffix);
+	int word_length;
+
+
+	while (fgets(word, MAX_WORD_LENGTH, words) != NULL) {
+		word_length = strlen(word) - 1;
+		word[word_length] = '\0';	/* remove \n  */
+		strcpy(unfolded_word, word);
+		if (fold) Fold(word);
+		cmp = strncmp(prefix, word, prefix_length);
+		if (cmp < 0) break;
+		if (cmp == 0)
+			if (suffix_length == 0 || word_length >= suffix_length
+			    && strcmp(suffix, word + word_length - suffix_length) == 0)
+				printf("%s\n", unfolded_word);
+	}
+  }
+
+  fclose(words);
+
+  exit(0);
+}
+
+
+
+Fold(str)
+char *str;
+
+{
+  while (*str) {
+	if (isupper(*str)) *str = *str - 'A' + 'a';
+	str++;
+  }
+}
+
+
+
+File_Error(word_file)
+char *word_file;
+
+{
+  perror(word_file);
+  exit(1);
+}