2 files changed, 22 insertions, 0 deletions
diff --git a/lib/lib.c b/lib/lib.c
index 8f8b4a3b..a6cb0ec3 100644
--- a/lib/lib.c
+++ b/lib/lib.c
@@ -1207,3 +1207,24 @@ char *getgroupname(gid_t gid)
   return gr ? gr->gr_name : gnum;
 }
 
+// Iterate over lines in file, calling function. Function can write 0 to
+// the line pointer if they want to keep it, or 1 to terminate processing,
+// otherwise line is freed. Passed file descriptor is closed at the end.
+void do_lines(int fd, void (*call)(char **pline, long len))
+{
+  FILE *fp = fd ? xfdopen(fd, "r") : stdin;
+
+  for (;;) {
+    char *line = 0;
+    ssize_t len;
+
+    len = getline(&line, (void *)&len, fp);
+    if (len > 0) {
+      call(&line, len);
+      if (line == (void *)1) break;
+      free(line);
+    } else break;
+  }
+
+  if (fd) fclose(fp);
+}
diff --git a/lib/lib.h b/lib/lib.h
index 43d6b1ff..5cd991c9 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -225,6 +225,7 @@ int regexec0(regex_t *preg, char *string, long len, int nmatch,
   regmatch_t pmatch[], int eflags);
 char *getusername(uid_t uid);
 char *getgroupname(gid_t gid);
+void do_lines(int fd, void (*call)(char **pline, long len));
 
 #define HR_SPACE 1 // Space between number and units
 #define HR_B     2 // Use "B" for single byte units