Determine if a word is spelled correctly

c/spellcheck.c

@@ -0,0 +1,108 @@
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <unistd.h>
+
+#define DICTIONARY "/usr/share/dict/words"
+
+struct trie {
+  struct trie *children[26];
+};
+
+void new_trie(struct trie *tree) {
+  uint8_t idx = 0;
+
+  for(; idx < 26; idx += 1) {
+    tree->children[idx] = NULL;
+  }
+}
+
+void trie_insert(struct trie *tree, const char *str, uint8_t len) {
+  struct trie *node = tree;
+  uint8_t idx = 0;
+
+  for(; idx < len; idx += 1) {
+    uint8_t pos = tolower(str[idx]) - 'a';
+
+    if(node->children[pos] == NULL) {
+      void *mem = malloc(sizeof(struct trie));
+
+      if(mem == NULL) {
+        fprintf(stderr, "could not allocate memory: %s\n", strerror(errno));
+        exit(1);
+      }
+
+      node->children[pos] = mem;
+      new_trie(node->children[pos]);
+    }
+
+    node = node->children[pos];
+  }
+}
+
+uint8_t trie_has(struct trie *tree, const char *str, uint8_t len) {
+  struct trie *node = tree;
+  uint8_t idx = 0;
+
+  for(; idx < len; idx += 1) {
+    uint8_t pos = tolower(str[idx]) - 'a';
+
+    if(node->children[pos] == NULL) {
+      return 0;
+    }
+
+    node = node->children[pos];
+  }
+
+  return 1;
+}
+
+int main(int argc, char **argv) {
+  struct trie dict;
+  new_trie(&dict);
+
+  int fd = open(DICTIONARY, O_RDONLY);
+
+  if(fd < 0) {
+    fprintf(stderr, "could not open %s: %s\n", DICTIONARY, strerror(errno));
+    return 1;
+  }
+
+  ssize_t bytes = 0;
+  char buf[1024] = { 0 };
+  char word[128] = { 0 };
+  uint8_t len = 0;
+
+  while((bytes = read(fd, buf, sizeof(buf))) > 0) {
+    ssize_t idx = 0;
+
+    for(; idx < bytes; idx += 1) {
+      if(buf[idx] == '\n') {
+        trie_insert(&dict, word, len);
+        len = 0;
+        bzero(word, sizeof(word));
+      } else if(len < sizeof(word)) {
+        word[len] = buf[idx];
+        len += 1;
+      }
+    }
+  }
+
+  if(bytes < 0) {
+    fprintf(stderr, "could not read from %s: %s\n", DICTIONARY, strerror(errno));
+    return 1;
+  }
+
+  const char *check = "paladin";
+
+  if(argc > 1) {
+    check = argv[1];
+  }
+
+  return !trie_has(&dict, check, strlen(check));
+}