chiark - git - mdw - termux-packages/blob - packages/command-not-found/command-not-found.c

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include <stdbool.h>
   4
   5 #define STRINGIFY(x) #x
   6 #define TOSTRING(x) STRINGIFY(x)
   7
   8 inline int termux_min3(unsigned int a, unsigned int b, unsigned int c) {
   9         return (a < b ? (a < c ? a : c) : (b < c ? b : c));
  10 }
  11
  12 int termux_levenshtein_distance(char const* restrict s1, char const* restrict s2) {
  13         unsigned int s1len = strlen(s1);
  14         unsigned int s2len = strlen(s2);
  15         unsigned int matrix[s2len+1][s1len+1];
  16         matrix[0][0] = 0;
  17         for (unsigned x = 1; x <= s2len; x++)
  18                 matrix[x][0] = matrix[x-1][0] + 1;
  19         for (unsigned y = 1; y <= s1len; y++)
  20                 matrix[0][y] = matrix[0][y-1] + 1;
  21         for (unsigned x = 1; x <= s2len; x++)
  22                 for (unsigned y = 1; y <= s1len; y++)
  23                         matrix[x][y] = termux_min3(matrix[x-1][y] + 1, matrix[x][y-1] + 1, matrix[x-1][y-1] + (s1[y-1] == s2[x-1] ? 0 : 1));
  24         return matrix[s2len][s1len];
  25 }
  26
  27 int main(int argc, char** argv) {
  28         if (argc != 2) {
  29                 fprintf(stderr, "usage: termux-command-not-found <command>\n");
  30                 return 1;
  31         }
  32         char* command_not_found = argv[1];
  33
  34         FILE* commands_file = fopen(TOSTRING(TERMUX_COMMANDS_LISTING), "r");
  35         if (commands_file == NULL) {
  36                 perror(TOSTRING(TERMUX_COMMANDS_LISTING));
  37                 return 1;
  38         }
  39
  40         int best_distance = -1;
  41         int guesses_at_best_distance = 0;
  42         char current_package[128];
  43         char best_package_guess[128];
  44         char best_command_guess[128];
  45         char* current_line = NULL;
  46         while (true) {
  47                 size_t buffer_length = sizeof(current_line);
  48                 ssize_t read_bytes = getline(&current_line, &buffer_length, commands_file);
  49                 if (read_bytes <= 1) break;
  50                 size_t line_length = strlen(current_line);
  51                 current_line[line_length-1] = 0;
  52                 if (current_line[0] == ' ') { // Binary
  53                         char* binary_name = current_line + 1;
  54                         int distance = termux_levenshtein_distance(command_not_found, binary_name);
  55                         if (distance == 0 && strcmp(command_not_found, binary_name) == 0) {
  56                                 printf("The program '%s' is currently not installed. You can install it by executing:\n apt install %s\n", binary_name, current_package);
  57                                 return 0;
  58                         } else if (best_distance == distance) {
  59                                 guesses_at_best_distance++;
  60                         } else if (best_distance == -1 || best_distance > distance) {
  61                                 guesses_at_best_distance = 0;
  62                                 best_distance = distance;
  63                                 strncpy(best_command_guess, binary_name, sizeof(best_command_guess));
  64                                 strncpy(best_package_guess, current_package, sizeof(best_package_guess));
  65                         }
  66                 } else { // Package
  67                         strncpy(current_package, current_line, sizeof(current_package));
  68                 }
  69         }
  70
  71         if (best_distance == -1 || best_distance > 3) {
  72                 printf("%s: command not found\n", command_not_found);
  73         } else {
  74                 printf("No command '%s' found, did you mean:\n", command_not_found);
  75                 printf(" Command '%s' from package '%s'\n", best_command_guess, best_package_guess);
  76         }
  77 }
  78