Add a basic command-not-find binary

diff --git a/packages/command-not-found/build.sh b/packages/command-not-found/build.sh
index 374372c..821b2c0 100644 (file)
--- a/packages/command-not-found/build.sh
+++ b/packages/command-not-found/build.sh
@@ -6,4 +6,10 @@ termux_step_make_install () {
        TERMUX_SHARE_DIR=$TERMUX_PREFIX/share/termux
        mkdir -p $TERMUX_SHARE_DIR
        cp $TERMUX_PKG_BUILDER_DIR/commands.txt $TERMUX_SHARE_DIR/commands.txt
+
+       TERMUX_LIBEXEC_DIR=$TERMUX_PREFIX/libexec/termux
+       mkdir -p $TERMUX_LIBEXEC_DIR
+       $CC $CFLAGS $LDFLAGS -std=c11 $TERMUX_PKG_BUILDER_DIR/command-not-found.c \
+               -DTERMUX_COMMANDS_LISTING=$TERMUX_PREFIX/share/termux/commands.txt \
+               -o $TERMUX_LIBEXEC_DIR/command-not-found
 }

diff --git a/packages/command-not-found/command-not-found.c b/packages/command-not-found/command-not-found.c
new file mode 100644 (file)
index 0000000..1c83a84
--- /dev/null
+++ b/packages/command-not-found/command-not-found.c
@@ -0,0 +1,78 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdbool.h>
+
+#define STRINGIFY(x) #x
+#define TOSTRING(x) STRINGIFY(x)
+
+inline int termux_min3(unsigned int a, unsigned int b, unsigned int c) {
+       return (a < b ? (a < c ? a : c) : (b < c ? b : c));
+}
+
+int termux_levenshtein_distance(char const* restrict s1, char const* restrict s2) {
+       unsigned int s1len = strlen(s1);
+       unsigned int s2len = strlen(s2);
+       unsigned int matrix[s2len+1][s1len+1];
+       matrix[0][0] = 0;
+       for (unsigned x = 1; x <= s2len; x++)
+               matrix[x][0] = matrix[x-1][0] + 1;
+       for (unsigned y = 1; y <= s1len; y++)
+               matrix[0][y] = matrix[0][y-1] + 1;
+       for (unsigned x = 1; x <= s2len; x++)
+               for (unsigned y = 1; y <= s1len; y++)
+                       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));
+       return matrix[s2len][s1len];
+}
+
+int main(int argc, char** argv) {
+       if (argc != 2) {
+               fprintf(stderr, "usage: termux-command-not-found <command>\n");
+               return 1;
+       }
+       char* command_not_found = argv[1];
+
+       FILE* commands_file = fopen(TOSTRING(TERMUX_COMMANDS_LISTING), "r");
+       if (commands_file == NULL) {
+               perror(TOSTRING(TERMUX_COMMANDS_LISTING));
+               return 1;
+       }
+
+       int best_distance = -1;
+       int guesses_at_best_distance = 0;
+       char current_package[128];
+       char best_package_guess[128];
+       char best_command_guess[128];
+       char* current_line = NULL;
+       while (true) {
+               size_t buffer_length = sizeof(current_line);
+               ssize_t read_bytes = getline(&current_line, &buffer_length, commands_file);
+               if (read_bytes <= 1) break;
+               size_t line_length = strlen(current_line);
+               current_line[line_length-1] = 0;
+               if (current_line[0] == ' ') { // Binary
+                       char* binary_name = current_line + 1;
+                       int distance = termux_levenshtein_distance(command_not_found, binary_name);
+                       if (distance == 0 && strcmp(command_not_found, binary_name) == 0) {
+                               printf("The program '%s' is currently not installed. You can install it by executing:\n apt install %s\n", binary_name, current_package);
+                               return 0;
+                       } else if (best_distance == distance) {
+                               guesses_at_best_distance++;
+                       } else if (best_distance == -1 || best_distance > distance) {
+                               guesses_at_best_distance = 0;
+                               best_distance = distance;
+                               strncpy(best_command_guess, binary_name, sizeof(best_command_guess));
+                               strncpy(best_package_guess, current_package, sizeof(best_package_guess));
+                       }
+               } else { // Package
+                       strncpy(current_package, current_line, sizeof(current_package));
+               }
+       }
+
+       if (best_distance == -1 || best_distance > 3) {
+               printf("%s: command not found\n", command_not_found);
+       } else {
+               printf("No command '%s' found, did you mean:\n", command_not_found);
+               printf(" Command '%s' from package '%s'\n", best_command_guess, best_package_guess);
+       }
+}
+