added simple `alias`ing system for commands

Signed-off-by: czjstmax <jstmaxlol@disroot.org>

2 files changed, 77 insertions, 4 deletions

diff --git a/README.md b/README.md
index 94c81ae..071cde5 100644
--- a/README.md
+++ b/README.md
@@ -9,3 +9,4 @@ an extended version of the [nosh minimal POSIX C shell](https://github.com/jstma
 -   doesn't quit on `^C`
 
 -   it also fixes some minor memory leaks and stuff from nosh.
+
diff --git a/nm.c b/nm.c
index ffe2605..2e694e8 100644
--- a/nm.c
+++ b/nm.c
@@ -17,8 +17,20 @@
 #include <readline/readline.h>
 #include <readline/history.h>
 
+#define MAX_ALIASES 256
+
+typedef struct {
+    char *dst;
+    char *src;
+} Alias;
+
+Alias aliases[MAX_ALIASES];
+int alias_count = 0;
+
 void handlecc(int sig);
+Alias CreateAlias(char *dst, char *src);
 void FreeAll();
+void FreeAliases();
 
 char *line = NULL;
 wordexp_t p;
@@ -28,7 +40,7 @@ int main(void)
     signal(SIGINT, handlecc);
     char *USER = getenv("USER");
     if (!USER)
-        USER = "god";
+        USER = "anon";
     char *HOME = getenv("HOME");
     if (!HOME)
         HOME = ".";
@@ -45,7 +57,7 @@ int main(void)
             add_history(line);
 
         if (wordexp(line, &p, 0) != 0) {
-            fprintf(stderr, "nsh+! parse error\n");
+            fprintf(stderr, "nsh+! ERROR while parsing\n");
             free(line);
             continue;
         }
@@ -57,6 +69,7 @@ int main(void)
         }
         if (strcmp(p.we_wordv[0], ":q") == 0 || strcmp(p.we_wordv[0], "exit") == 0) {
             FreeAll();
+            FreeAliases();
             return 0;
         }
         else if (strcmp(p.we_wordv[0], "echo") == 0) {
@@ -68,6 +81,26 @@ int main(void)
                 else continue;
             }
         }
+        else if (strcmp(p.we_wordv[0], "alias") == 0) {
+            if (p.we_wordc <= 2) {
+                fprintf(stderr, "nsh+! ERROR: expected 2 args\n");
+            } else {
+                // overwrite if exists
+                bool found = false;
+                for (int i = 0; i < alias_count; i++) {
+                    if (strcmp(aliases[i].dst, p.we_wordv[1]) == 0) {
+                        free(aliases[i].src);
+                        aliases[i].src = strdup(p.we_wordv[2]);
+                        found = true;
+                        break;
+                    }
+                }
+
+                if (!found && alias_count < MAX_ALIASES) {
+                    aliases[alias_count++] = CreateAlias(p.we_wordv[1], p.we_wordv[2]);
+                }
+            }
+        }
         else if (strcmp(p.we_wordv[0], "cd") == 0) {
             if (p.we_wordc <= 1) {
                 if (chdir(HOME))
@@ -84,19 +117,41 @@ int main(void)
         }
         else if (strcmp(p.we_wordv[0], "help") == 0) {
             printf(
-                "noshmore\n"
+                "noshmore\tALIASES(%d)\n"
                 "an extended version of nosh, the minimal POSIX C shell.\n"
                 "\n"
                 "built-ins:\n"
                 "echo  -> outputs a string of text, doesn't need \" enclosure.\n"
                 "         supports '-c' for output without '\\n'"
                 "clear -> clears screen (and scrollback)\n"
+                "alias -> creates non-persistent command aliases\n"
+                "         (i.e. alias v vim)\n"
                 "cd    -> change working directory\n"
                 "help  -> prints this screen\n"
                 "\ngithub repo: github.com/jstmaxlol/noshmore\n"
+                , MAX_ALIASES
             );
         }
         else {
+            for (int i = 0; i < alias_count; i++) {
+                if (strcmp(p.we_wordv[0], aliases[i].dst) == 0) {
+                    char new_line[81920] = {0};
+                    strcat(new_line, aliases[i].src);
+
+                    for (size_t j = 1; j < p.we_wordc; j++) {
+                        strcat(new_line, " ");
+                        strcat(new_line, p.we_wordv[j]);
+                    }
+
+                    wordfree(&p);
+                    if (wordexp(new_line, &p, 0) != 0) {
+                        fprintf(stderr, "nsh+! ERROR: alias expansion failed\n");
+                        break;
+                    }
+
+                    break;
+                }
+            }
             pid_t pid = fork();
             char **argv = p.we_wordv; // pray with me now
             if (pid == 0) {
@@ -110,7 +165,7 @@ int main(void)
                 waitpid(pid, &status, 0);
             }
             else {
-                fprintf(stderr, "nsh+! ERROR: couldn't execute %s\n", p.we_wordv[0]);
+                fprintf(stderr, "nsh+! ERROR: %s not found\n", p.we_wordv[0]);
             }
         }
     }
@@ -125,6 +180,14 @@ void handlecc(int sig)
     rl_redisplay();
 }
 
+Alias CreateAlias(char *dst, char *src)
+{
+    Alias alias;
+    alias.dst = strdup(dst);
+    alias.src = strdup(src);
+    return alias;
+}
+
 void FreeAll()
 {
     wordfree(&p);
@@ -132,3 +195,12 @@ void FreeAll()
     line = NULL;
 }
 
+void FreeAliases()
+{
+    for (int i = 0; i < alias_count; i++) {
+        free(aliases[i].dst);
+        free(aliases[i].src);
+    }
+
+}
+