Allow apr_proc_create() to call an app-provided error reporting

function when apr_proc_create() fails in the new child process
after fork().  The app-provided error reporting function will only
be called on platforms where apr_proc_create() first calls
fork() to create the new process.


git-svn-id: http://svn.apache.org/repos/asf/apr/apr/trunk@64330 13f79535-47bb-0310-9956-ffa450edef68

8 files changed, 82 insertions, 0 deletions

diff --git a/CHANGES b/CHANGES
index e3551ec74..15150f218 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,5 +1,11 @@
 Changes with APR 0.9.2
 
+  *) Allow apr_proc_create() to call an app-provided error reporting
+     function when apr_proc_create() fails in the new child process
+     after fork().  The app-provided error reporting function will only
+     be called on platforms where apr_proc_create() first calls
+     fork() to create the new process.  [Jeff Trawick]
+
   *) Rename rules.mk to apr_rules.mk and make apr_rules.mk be installed.
      [Thom May]
      
diff --git a/include/apr_thread_proc.h b/include/apr_thread_proc.h
index f64d13435..0e4b514a6 100644
--- a/include/apr_thread_proc.h
+++ b/include/apr_thread_proc.h
@@ -177,6 +177,19 @@ struct apr_proc_t {
 #endif
 };
 
+/**
+ * The prototype for APR child errfn functions.  (See the description
+ * of apr_procattr_child_errfn_set() for more information.)
+ * It is passed the following parameters:
+ * @param pool Pool associated with the apr_proc_t.  If your child
+ *             error function needs user data, associate it with this
+ *             pool.
+ * @param err APR error code describing the error
+ * @param description Text description of type of processing which failed
+ */
+typedef void (apr_child_errfn_t)(apr_pool_t *proc, apr_status_t err,
+                                 const char *description);
+
 /** Opaque Thread structure. */
 typedef struct apr_thread_t           apr_thread_t;
 /** Opaque Thread attributes structure. */
@@ -487,6 +500,18 @@ APR_DECLARE(apr_status_t) apr_procattr_limit_set(apr_procattr_t *attr,
                                                 struct rlimit *limit);
 #endif
 
+/**
+ * Specify an error function to be called in the child process if APR
+ * encounters an error in the child prior to running the specified program.
+ * @param child_errfn The function to call in the child process.
+ * @param userdata Parameter to be passed to errfn.
+ * @remark At the present time, it will only be called from apr_proc_create()
+ *         on platforms where fork() is used.  It will never be called on other
+ *         platforms.
+ */
+APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
+                                                       apr_child_errfn_t *errfn);
+
 #if APR_HAS_FORK
 /**
  * This is currently the only non-portable call in APR.  This executes 
diff --git a/include/arch/unix/apr_arch_threadproc.h b/include/arch/unix/apr_arch_threadproc.h
index 002c8f701..960db1e50 100644
--- a/include/arch/unix/apr_arch_threadproc.h
+++ b/include/arch/unix/apr_arch_threadproc.h
@@ -134,6 +134,7 @@ struct apr_procattr_t {
 #ifdef RLIMIT_NOFILE
     struct rlimit *limit_nofile;
 #endif
+    apr_child_errfn_t *errfn;
 };
 
 #endif  /* ! THREAD_PROC_H */
diff --git a/threadproc/beos/proc.c b/threadproc/beos/proc.c
index e97085581..7bfa3f77f 100644
--- a/threadproc/beos/proc.c
+++ b/threadproc/beos/proc.c
@@ -203,6 +203,12 @@ APR_DECLARE(apr_status_t) apr_proc_fork(apr_proc_t *proc, apr_pool_t *pool)
     return APR_INPARENT;
 }
 
+APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
+                                                       apr_child_errfn_t *errfn)
+{
+    /* won't ever be called on this platform, so don't save the function pointer */
+    return APR_SUCCESS;
+}
 
 APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *new, const char *progname, 
                                           const char * const *args,
diff --git a/threadproc/netware/proc.c b/threadproc/netware/proc.c
index 4ca612d64..537d22e93 100644
--- a/threadproc/netware/proc.c
+++ b/threadproc/netware/proc.c
@@ -283,6 +283,13 @@ static apr_status_t limit_proc(apr_procattr_t *attr)
     return APR_SUCCESS;
 }
 
+APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
+                                                       apr_child_errfn_t *errfn)
+{
+    /* won't ever be called on this platform, so don't save the function pointer */
+    return APR_SUCCESS;
+}
+
 APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *newproc,
 									const char *progname, 
 									const char * const *args, 
diff --git a/threadproc/os2/proc.c b/threadproc/os2/proc.c
index 75b4237bf..7afe711fe 100644
--- a/threadproc/os2/proc.c
+++ b/threadproc/os2/proc.c
@@ -278,6 +278,15 @@ static char *double_quotes(apr_pool_t *pool, const char *str)
 
 
 
+APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
+                                                       apr_child_errfn_t *errfn)
+{
+    /* won't ever be called on this platform, so don't save the function pointer */
+    return APR_SUCCESS;
+}
+
+
+
 APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *proc, const char *progname,
                                           const char * const *args,
                                           const char * const *env,
diff --git a/threadproc/unix/proc.c b/threadproc/unix/proc.c
index 8c07e8cf9..a57f76ad1 100644
--- a/threadproc/unix/proc.c
+++ b/threadproc/unix/proc.c
@@ -295,6 +295,13 @@ static apr_status_t limit_proc(apr_procattr_t *attr)
     return APR_SUCCESS;
 }
 
+APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
+                                                       apr_child_errfn_t *errfn)
+{
+    attr->errfn = errfn;
+    return APR_SUCCESS;
+}
+
 APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *new,
                                           const char *progname,
                                           const char * const *args,
@@ -368,11 +375,17 @@ APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *new,
 
         if (attr->currdir != NULL) {
             if (chdir(attr->currdir) == -1) {
+                if (attr->errfn) {
+                    attr->errfn(pool, errno, "change of working directory failed");
+                }
                 exit(-1);   /* We have big problems, the child should exit. */
             }
         }
 
         if ((status = limit_proc(attr)) != APR_SUCCESS) {
+            if (attr->errfn) {
+                attr->errfn(pool, errno, "setting of resource limits failed");
+            }
             exit(-1);   /* We have big problems, the child should exit. */
         }
 
@@ -422,6 +435,14 @@ APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *new,
 
             execvp(progname, (char * const *)args);
         }
+        if (attr->errfn) {
+            char *desc;
+
+            desc = apr_psprintf(pool, "exec of '%s' failed",
+                                progname);
+            attr->errfn(pool, errno, desc);
+        }
+
         exit(-1);  /* if we get here, there is a problem, so exit with an
                     * error code. */
     }
diff --git a/threadproc/win32/proc.c b/threadproc/win32/proc.c
index aa2e4a62a..fa80a9b12 100644
--- a/threadproc/win32/proc.c
+++ b/threadproc/win32/proc.c
@@ -281,6 +281,13 @@ static char *apr_caret_escape_args(apr_pool_t *p, const char *str)
     return cmd;
 }
 
+APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
+                                                       apr_child_errfn_t *errfn)
+{
+    /* won't ever be called on this platform, so don't save the function pointer */
+    return APR_SUCCESS;
+}
+
 APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *new,
                                           const char *progname,
                                           const char * const *args,