bore

commit 75094f44e6c8dc65cbf6ac9c680aae419538538d
parent 071fb3b64f2823167e31a17d6742086392c74943
Author: phoebos <ben@bvnf.space>
Date:   Tue, 11 Jan 2022 22:54:42 +0000

pwd: add

Diffstat:
M
Makefile
 | 
1
+
M
PROGRESS
 | 
2
+-
M
TODO.posix
 | 
2
+-
A
pwd.c
 | 
69
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

4 files changed, 72 insertions(+), 2 deletions(-)
diff --git a/Makefile b/Makefile
@@ -9,6 +9,7 @@ BINS = \
 	head \
 	ls \
 	mkdir \
+	pwd \
 	sort \
 	tee \
 	true \
diff --git a/PROGRESS b/PROGRESS
@@ -29,7 +29,7 @@
 [ ] nl
 [ ] printf
 [ ] ps
-[ ] pwd
+[x] pwd [-LP]
 [ ] rm
 [ ] rmdir
 [ ] shred
diff --git a/TODO.posix b/TODO.posix
@@ -83,7 +83,7 @@
 [ ] printf
 [ ] prs
 [ ] ps
-[ ] pwd
+[x] pwd
 [ ] renice
 [ ] rm
 [ ] rmdir
diff --git a/pwd.c b/pwd.c
@@ -0,0 +1,69 @@
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+int
+main(int argc, char **argv) {
+    int c, flag_L = 1;
+    long size;
+    while ((c = getopt(argc, argv, "LP")) != -1) {
+        switch (c) {
+            case 'L':
+                flag_L = 1;
+                break;
+            case 'P':
+                flag_L = 0;
+                break;
+            case '?':
+                fprintf(stderr, "usage: %s [-L|-P]\n", argv[0]);
+                return 1;
+        }
+    }
+
+    if (flag_L) {
+        char *cwd = getenv("PWD");
+        if (cwd == NULL)
+            goto flag_P;
+        else if (*cwd != '/')
+            goto flag_P;
+        else if (strstr(cwd, "/./") != NULL)
+            goto flag_P;
+        else if (strstr(cwd, "/../") != NULL)
+            goto flag_P;
+
+        /* POSIX.1-2017 does not specify what to do if $PWD is longer than PATH_MAX bytes;
+         * this implementation chooses to print the pathname found from PWD in this case.
+         */
+
+        puts(cwd);
+        return 0;
+    }
+
+flag_P:
+    size = pathconf(".", _PC_PATH_MAX);
+    if (size == -1)
+        size = PATH_MAX;
+
+    char *buf = NULL;
+    for (char *tmp = NULL; tmp == NULL; size += 32) {
+        buf = realloc(buf, size);
+        if (buf == NULL) {
+            perror("pwd");
+            return 1;
+        }
+
+        errno = 0;
+        tmp = getcwd(buf, size);
+        if (tmp == NULL && errno != ERANGE) {
+            perror("pwd");
+            return 1;
+        }
+    }
+
+    puts(buf);
+    free(buf);
+    return 0;
+}