commit 6d50d4cbbf6ff34ed68dba61d30c434b57b23332
author Rob Landley <rob@landley.net> Tue May 17 12:10:07 2016 -0500
committer Rob Landley <rob@landley.net> Tue May 17 12:10:07 2016 -0500
tree 68dfe801c6a0f09f51a54d72bf957998031b35e4
parent 713055b349b2e6adc7ada2640cd7a40b3d311fb6

Add bufgetpwuid. (Repeated calls to getpwuid() are really expensive.)

lib/lib.c

diff --git a/lib/lib.c b/lib/lib.c
index 0df45bf..98597b2 100644
--- a/lib/lib.c
+++ b/lib/lib.c
@@ -1074,3 +1074,31 @@
 {
   return (minor&0xff)|((major&0xfff)<<8)|((minor&0xfff00)<<12);
 }
+
+// Return cached passwd entries.
+struct passwd *bufgetpwuid(uid_t uid)
+{
+  struct pwuidbuf_list {
+    struct pwuidbuf_list *next;
+    struct passwd pw;
+  } *list;
+  struct passwd *temp;
+  static struct pwuidbuf_list *pwuidbuf;
+
+  for (list = pwuidbuf; list; list = list->next)
+    if (list->pw.pw_uid == uid) return &(list->pw);
+
+  list = xmalloc(512);
+  list->next = pwuidbuf;
+
+  errno = getpwuid_r(uid, &list->pw, sizeof(*list)+(char *)list,
+    512-sizeof(*list), &temp);
+  if (!temp) {
+    free(list);
+
+    return 0;
+  }
+  pwuidbuf = list;
+
+  return &list->pw;
+}

lib/lib.h

diff --git a/lib/lib.h b/lib/lib.h
index aafa969..b1f4ca1 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -205,6 +205,7 @@
 int dev_minor(int dev);
 int dev_major(int dev);
 int dev_makedev(int major, int minor);
+struct passwd *bufgetpwuid(uid_t uid);
 
 #define HR_SPACE 1 // Space between number and units
 #define HR_B     2 // Use "B" for single byte units

toys/posix/ps.c

diff --git a/toys/posix/ps.c b/toys/posix/ps.c
index 9557b64..445228f 100644
--- a/toys/posix/ps.c
+++ b/toys/posix/ps.c
@@ -453,7 +453,7 @@
 
         if (gr) out = gr->gr_name;
       } else {
-        struct passwd *pw = getpwuid(ll);
+        struct passwd *pw = bufgetpwuid(ll);
 
         if (pw) out = pw->pw_name;
       }