Component walkpopen

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Component walkpopen

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Type	Function
Summary	Walk the output of a process
Description	Each lines (text) is sent to the oneline functag. It returns the number of line processed, or -1 if some errors.

		void empty (const char *command)
		void end ()
		void fail (const char *command)
		void init (FILE *fout, bool &end)
		int oneerr (const char line, const char command, FILE *fout)
		int oneline (const char line, int noline, FILE fout)
		void start (FILE *fout, bool &end)

Examples

sample / walkpopen component

Prototypes

int walkpopen (const char *command, int timeout, bool user)

Normally walkpopen change to the root directory before executing a command. Further, it cleans up the environment. This is normally used by privileged program to avoid security hole. If you are writting an end user application (no privilege), you may want to set the parameter "user" to true to avoid this directory changing and environment variables filtering.

int walkpopen (const char *cmdname, const char *arg, int timeout)

The command name is just a name. It is looked up in the resource database to locate its path. If the path is already known, an absolute path may be specified instead.

int walkpopen (const char *cmd, int timeout)

Return the end status of the process.

Functags

void empty (const char *command) Optional: Called when the process exits without any output
void end () Optional: Called after having processed the last output line
void fail (const char *command) Optional: Called when the command failed to execute
void init (FILE *fout, bool &end) Optional: Called at the beginning of the session
This is used to send some input to the sub-process so it can start to work
int oneerr (const char *line, const char *command, FILE *fout) Optional: Is called for every error message sent by the process (every line)
This function must return 0 to continue, -1 to force walkpopen to exit.
int oneline (const char *line, int noline, FILE *fout) Mandatory: Is called for every line of text sent by the process (on standard output)
Must return -1 if we want the processing to stop.
void start (FILE *fout, bool &end) Optional: Called before processing the first output line

Fhelpers

void close_input (): Close the input of the sub-process
After sending some information to the sub-process, we close its input. The sub-process receives an end-of-file condition and generally ends its processing.