add apr_procattr_error_check_set() for telling apr_proc_create() to

try to anticipate any errors that might occur after fork()
(no-op everywhere but Unix)


git-svn-id: http://svn.apache.org/repos/asf/apr/apr/trunk@64341 13f79535-47bb-0310-9956-ffa450edef68

8 files changed, 82 insertions, 5 deletions

diff --git a/CHANGES b/CHANGES
index b91a1df66..51cdd495e 100644
--- a/CHANGES
+++ b/CHANGES
@@ -8,11 +8,10 @@ Changes with APR 0.9.2
      .pdb symbol files.)  Documentation on how-to-use these symbol files
      will be forthcoming.  [Allen Edwards, William Rowe]
 
-  *) 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]
+  *) Add two new proc attributes to improve diagnostics for 
+     apr_proc_create() failures on platforms where fork()+exec() is used.
+     See the doc for apr_procattr_child_errfn_set() and
+     apr_procattr_error_check_set().  [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 0e4b514a6..435082f57 100644
--- a/include/apr_thread_proc.h
+++ b/include/apr_thread_proc.h
@@ -512,6 +512,20 @@ APR_DECLARE(apr_status_t) apr_procattr_limit_set(apr_procattr_t *attr,
 APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
                                                        apr_child_errfn_t *errfn);
 
+/**
+ * Specify that apr_proc_create() should do whatever it can to report
+ * failures to the caller of apr_proc_create(), rather than find out in
+ * the child.
+ * @param chk Flag to indicate whether or not extra work should be done
+ *            to try to report failures to the caller.
+ * @remark This flag only affects apr_proc_create() on platforms where
+ *         fork() is used.  This leads to extra overhead in the calling
+ *         process, but that may help the application handle such
+ *         errors more gracefully.
+ */
+APR_DECLARE(apr_status_t) apr_procattr_error_check_set(apr_procattr_t *attr,
+                                                       apr_int32_t chk);
+
 #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 960db1e50..6de6cc275 100644
--- a/include/arch/unix/apr_arch_threadproc.h
+++ b/include/arch/unix/apr_arch_threadproc.h
@@ -135,6 +135,7 @@ struct apr_procattr_t {
     struct rlimit *limit_nofile;
 #endif
     apr_child_errfn_t *errfn;
+    apr_int32_t errchk;
 };
 
 #endif  /* ! THREAD_PROC_H */
diff --git a/threadproc/beos/proc.c b/threadproc/beos/proc.c
index 7bfa3f77f..031debc60 100644
--- a/threadproc/beos/proc.c
+++ b/threadproc/beos/proc.c
@@ -210,6 +210,13 @@ APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
     return APR_SUCCESS;
 }
 
+APR_DECLARE(apr_status_t) apr_procattr_error_check_set(apr_procattr_t *attr,
+                                                       apr_int32_t chk)
+{
+    /* won't ever be used on this platform, so don't save the flag */
+    return APR_SUCCESS;
+}
+
 APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *new, const char *progname, 
                                           const char * const *args,
                                           const char * const *env, 
diff --git a/threadproc/netware/proc.c b/threadproc/netware/proc.c
index 537d22e93..c51d8e9ea 100644
--- a/threadproc/netware/proc.c
+++ b/threadproc/netware/proc.c
@@ -290,6 +290,13 @@ APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
     return APR_SUCCESS;
 }
 
+APR_DECLARE(apr_status_t) apr_procattr_error_check_set(apr_procattr_t *attr,
+                                                       apr_int32_t chk)
+{
+    /* won't ever be used on this platform, so don't save the flag */
+    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 7afe711fe..45ab03d26 100644
--- a/threadproc/os2/proc.c
+++ b/threadproc/os2/proc.c
@@ -287,6 +287,15 @@ APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
 
 
 
+APR_DECLARE(apr_status_t) apr_procattr_error_check_set(apr_procattr_t *attr,
+                                                       apr_int32_t chk)
+{
+    /* won't ever be used on this platform, so don't save the flag */
+    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 a57f76ad1..015fe04c3 100644
--- a/threadproc/unix/proc.c
+++ b/threadproc/unix/proc.c
@@ -302,6 +302,13 @@ APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
     return APR_SUCCESS;
 }
 
+APR_DECLARE(apr_status_t) apr_procattr_error_check_set(apr_procattr_t *attr,
+                                                       apr_int32_t chk)
+{
+    attr->errchk = chk;
+    return APR_SUCCESS;
+}
+
 APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *new,
                                           const char *progname,
                                           const char * const *args,
@@ -316,6 +323,32 @@ APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *new,
     new->err = attr->parent_err;
     new->out = attr->parent_out;
 
+    if (attr->errchk) {
+        if (attr->currdir) {
+            if (access(attr->currdir, R_OK|X_OK) == -1) {
+                /* chdir() in child wouldn't have worked */
+                return errno;
+            }
+        }
+
+        if (attr->cmdtype == APR_PROGRAM ||
+            attr->cmdtype == APR_PROGRAM_ENV ||
+            *progname == '/') {
+            /* for both of these values of cmdtype, caller must pass
+             * full path, so it is easy to check;
+             * caller can choose to pass full path for other
+             * values of cmdtype
+             */
+            if (access(progname, R_OK|X_OK) == -1) {
+                /* exec*() in child wouldn't have worked */
+                return errno;
+            }
+        }
+        else {
+            /* todo: search PATH for progname then try to access it */
+        }
+    }
+
     if ((new->pid = fork()) < 0) {
         return errno;
     }
diff --git a/threadproc/win32/proc.c b/threadproc/win32/proc.c
index fa80a9b12..02b6f57f0 100644
--- a/threadproc/win32/proc.c
+++ b/threadproc/win32/proc.c
@@ -288,6 +288,13 @@ APR_DECLARE(apr_status_t) apr_procattr_child_errfn_set(apr_procattr_t *attr,
     return APR_SUCCESS;
 }
 
+APR_DECLARE(apr_status_t) apr_procattr_error_check_set(apr_procattr_t *attr,
+                                                       apr_int32_t chk)
+{
+    /* won't ever be used on this platform, so don't save the flag */
+    return APR_SUCCESS;
+}
+
 APR_DECLARE(apr_status_t) apr_proc_create(apr_proc_t *new,
                                           const char *progname,
                                           const char * const *args,