Merge git://git.kernel.org/pub/scm/gitk/gitk

[git.git] / run-command.h

diff --git a/run-command.h b/run-command.h
index e9c84d03639a59178e16361ee70df95835b9beb3..debe3074b5a01fb5a19e61f07ff66c250cdc4f82 100644 (file)
--- a/run-command.h
+++ b/run-command.h
@@ -14,6 +14,24 @@ enum {
 struct child_process {
        const char **argv;
        pid_t pid;
+       /*
+        * Using .in, .out, .err:
+        * - Specify 0 for no redirections (child inherits stdin, stdout,
+        *   stderr from parent).
+        * - Specify -1 to have a pipe allocated as follows:
+        *     .in: returns the writable pipe end; parent writes to it,
+        *          the readable pipe end becomes child's stdin
+        *     .out, .err: returns the readable pipe end; parent reads from
+        *          it, the writable pipe end becomes child's stdout/stderr
+        *   The caller of start_command() must close the returned FDs
+        *   after it has completed reading from/writing to it!
+        * - Specify > 0 to set a channel to a particular FD as follows:
+        *     .in: a readable FD, becomes child's stdin
+        *     .out: a writable FD, becomes child's stdout/stderr
+        *     .err > 0 not supported
+        *   The specified FD is closed by start_command(), even in case
+        *   of errors!
+        */
        int in;
        int out;
        int err;