Initial revision

darcs-hash:20050920132639-ac50b-fa3b476891e1f5f67207cf4cc7bf623834cc5edc.gz

exec.h

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+/** \file exec.h
+	Prototypes for functions for executing a program
+*/
+
+/**
+  Execute the processes specified by j. 
+
+   I've put a fair bit of work into making builtins behave like other
+   programs as far as pipes are concerned. Unlike i.e. bash, builtins
+   can pipe to other builtins with arbitrary amounts of data, and so
+   on. To do this, after a builtin is run in the real process, it
+   forks and a dummy process is created, responsible for writing the
+   output of the builtin. This is surprisingly cheap on my computer,
+   probably because of the marvels of copy on write forking.
+
+   This rule is short circuted in the case where a builtin does not
+   output to a pipe and does in fact not output anything. The speed
+   improvement from this optimization is not noticable on a normal
+   computer/OS in regular use, but the promiscous amounts of forking
+   that resulted was responsible for a huge slowdown when using
+   Valgrind as well as when doing complex command-specific
+   completions.
+
+
+*/
+void exec( job_t *j );
+
+/**
+  Evaluate the expression cmd in a subshell, add the outputs into the
+  list l. On return, the status flag as returned bu \c
+  proc_gfet_last_status will not be changed.
+
+  \param cmd the command to execute
+  \param l The list to insert output into.If \c l is zero, the output will be discarded.
+
+  \return the status of the last job to exit, or -1 if en error was encountered.
+*/
+int exec_subshell( const wchar_t *cmd, 
+				   array_list_t *l );
+
+void exec_free_io_buffer( io_data_t *io_buffer );
+io_data_t *exec_make_io_buffer();
+