From 5b95d256387b45fbe33f7ee7890ae35afdd5c371 Mon Sep 17 00:00:00 2001
From: Joe Orton <jorton@apache.org>
Date: Fri, 13 Mar 2020 14:34:18 +0000
Subject: [PATCH] * server/log.c (ap_log_pid): Use a temporary file, then
 rename once   successfully written; also add error checking.  Avoids startup 
  failures if a previous httpd invocation crashed while writing the   pidfile.

Submitted by: Nicolas Carrier <carrier.nicolas0 gmail.com>, jorton
Github: closes #100, closes #69
PR: 63140

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1875153 13f79535-47bb-0310-9956-ffa450edef68
Signed-off-by: Nicolas Carrier <nicolas.carrier@orolia.com>
---
 server/log.c | 33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/server/log.c b/server/log.c
index f0bde6e4b8..8d54b4e057 100644
--- a/server/log.c
+++ b/server/log.c
@@ -1598,6 +1598,9 @@ AP_DECLARE(void) ap_log_pid(apr_pool_t *p, const char *filename)
     pid_t mypid;
     apr_status_t rv;
     const char *fname;
+    char *temp_fname;
+    apr_fileperms_t perms;
+    char pidstr[64];
 
     if (!filename) {
         return;
@@ -1626,19 +1629,35 @@ AP_DECLARE(void) ap_log_pid(apr_pool_t *p, const char *filename)
                       fname);
     }
 
-    if ((rv = apr_file_open(&pid_file, fname,
-                            APR_WRITE | APR_CREATE | APR_TRUNCATE,
-                            APR_UREAD | APR_UWRITE | APR_GREAD | APR_WREAD, p))
-        != APR_SUCCESS) {
+    temp_fname = apr_pstrcat(p, fname, ".XXXXXX", NULL);
+    rv = apr_file_mktemp(&pid_file, temp_fname,
+                         APR_FOPEN_WRITE | APR_FOPEN_CREATE | APR_FOPEN_TRUNCATE, p);
+    if (rv != APR_SUCCESS) {
         ap_log_error(APLOG_MARK, APLOG_ERR, rv, NULL, APLOGNO(00099)
-                     "could not create %s", fname);
+                     "could not create %s", temp_fname);
         ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL, APLOGNO(00100)
                      "%s: could not log pid to file %s",
                      ap_server_argv0, fname);
         exit(1);
     }
-    apr_file_printf(pid_file, "%" APR_PID_T_FMT APR_EOL_STR, mypid);
-    apr_file_close(pid_file);
+
+    apr_snprintf(pidstr, sizeof pidstr, "%" APR_PID_T_FMT APR_EOL_STR, mypid);
+
+    perms = APR_UREAD | APR_UWRITE | APR_GREAD | APR_WREAD;
+    rv = apr_file_perms_set(temp_fname, perms);    
+    if (rv == APR_SUCCESS)
+        rv = apr_file_write_full(pid_file, pidstr, strlen(pidstr), NULL);
+    if (rv == APR_SUCCESS)
+        rv = apr_file_close(pid_file);
+    if (rv == APR_SUCCESS)
+        rv = apr_file_rename(temp_fname, fname, p);
+    if (rv != APR_SUCCESS) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, rv, NULL, APLOGNO(10231)
+                     "%s: Failed creating pid file %s",
+                     ap_server_argv0, temp_fname);
+        exit(1);
+    }
+
     saved_pid = mypid;
 }
 
-- 
2.25.2