1 files changed, 81 insertions, 9 deletions
diff --git a/lib/get_pid.c b/lib/get_pid.c
index 383eb69..af3f2f8 100644
--- a/lib/get_pid.c
+++ b/lib/get_pid.c
@@ -10,22 +10,94 @@
 
 #include "prototypes.h"
 #include "defines.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 
-int get_pid (const char *pidstr, pid_t *pid)
+#include "string/sprintf.h"
+
+
+int
+get_pid(const char *pidstr, pid_t *pid)
 {
-	long long int val;
-	char *endptr;
+	char       *end;
+	long long  val;
 
 	errno = 0;
-	val = strtoll (pidstr, &endptr, 10);
+	val = strtoll(pidstr, &end, 10);
 	if (   ('\0' == *pidstr)
-	    || ('\0' != *endptr)
-	    || (ERANGE == errno)
+	    || ('\0' != *end)
+	    || (0 != errno)
+	    || (val < 1)
 	    || (/*@+longintegral@*/val != (pid_t)val)/*@=longintegral@*/) {
-		return 0;
+		return -1;
 	}
 
-	*pid = (pid_t)val;
-	return 1;
+	*pid = val;
+	return 0;
 }
 
+/*
+ * If use passed in fd:4 as an argument, then return the
+ * value '4', the fd to use.
+ * On error, return -1.
+ */
+int get_pidfd_from_fd(const char *pidfdstr)
+{
+	char         *end;
+	long long    val;
+	struct stat  st;
+	dev_t proc_st_dev, proc_st_rdev;
+
+	errno = 0;
+	val = strtoll(pidfdstr, &end, 10);
+	if (   ('\0' == *pidfdstr)
+	    || ('\0' != *end)
+	    || (0 != errno)
+	    || (val < 0)
+	    || (/*@+longintegral@*/val != (int)val)/*@=longintegral@*/) {
+		return -1;
+	}
+
+	if (stat("/proc/self/uid_map", &st) < 0) {
+		return -1;
+	}
+
+	proc_st_dev = st.st_dev;
+	proc_st_rdev = st.st_rdev;
+
+	if (fstat(val, &st) < 0) {
+		return -1;
+	}
+
+	if (st.st_dev != proc_st_dev || st.st_rdev != proc_st_rdev) {
+		return -1;
+	}
+
+	return (int)val;
+}
+
+int open_pidfd(const char *pidstr)
+{
+	int    proc_dir_fd;
+	char   proc_dir_name[32];
+	pid_t  target;
+
+	if (get_pid(pidstr, &target) == -1)
+		return -ENOENT;
+
+	/* max string length is 6 + 10 + 1 + 1 = 18, allocate 32 bytes */
+	if (SNPRINTF(proc_dir_name, "/proc/%u/", target) == -1) {
+		fprintf(stderr, "snprintf of proc path failed for %u: %s\n",
+			target, strerror(errno));
+		return -EINVAL;
+	}
+
+	proc_dir_fd = open(proc_dir_name, O_DIRECTORY);
+	if (proc_dir_fd < 0) {
+		fprintf(stderr, _("Could not open proc directory for target %u: %s\n"),
+			target, strerror(errno));
+		return -EINVAL;
+	}
+	return proc_dir_fd;
+}