stcall(3)

NAME
stCallEditor, stCallCmd, stCallCmdErrno, stFindProgram - call command processor with command string

SYNOPSIS
#include <config.h>
#include <sttk.h.h>

int    stCallEditor (char *editor, char *file, char *contents, char **newcontents);

int    stCallCmd (char *commandProcessor, char *commandString);

int    stCallCmdErrno;

char*    stFindProgram (char *fileName)

DESCRIPTION
stCallEditor calls editor editor with file file and returns its contents after the editor session in newcontents. Return value is the length of the new text. On failure, 0 is returned to indicate the error. Newcontents is not updated and points to nowhere. On error the file will be removed. If contents points to a valid text, this text is put (not appended) into the temporary file before editor starts. Contents must be NULL terminated, otherwise strange things will happen.

stCallCmd invokes commandProcessor as a child process and writes commandString to its standard input. The current process waits for termination of the child process. stCallCmd returns the exit status of the child process reported by wait(2). The commandProcessor string may contain command line arguments to the command processor, separated by whitespace. (This is necessary for some programs to make them read commands from standard input.) The command processor program is searched for in the directories given in the environment variable PATH. If commandString does not end with a newline, a newline is added.

stFindProgram returns the full pathname of programName if program is found and executable. Otherwise NULL.

ENVIRONMENT

PATH
    List of colon-separated directoriy names where execvp(3) searches for the program to execute (default /bin:/usr/bin:/usr/ucb).

SEE ALSO
wait(2)

DIAGNOSTICS
On a successful call stCallCmd returns the exit status of the child process. If an error occured, stCallCmd returns a negative number as defined in sttk.h:

CMDPROC_EMPTY
    An empty or NULL string has been supplied for commandProcessor.

NO_MORE_CORE
    A call to malloc(3) or calloc(3) returned a NULL pointer.

FORK_FAILED
    fork(2) could not create a child process.

PIPE_FAILED
    A call to pipe(2) failed.

WAIT_ERROR
    A call to wait(2) failed.

EXEC_FAILED
    execvp(3) could not execute commandProcessor.

CHILD_KILLED
    The child process was killed by an uncaught signal.

WRITE_FAILED
    write(2) could not write commandString to the pipe. This usually happens when commandProcessor does not read its standard input and terminates before commandString is written.

NO_PROGRAM
    commandProcessor could not be found.

For the most error conditions the integer variable stCallCmdErrno (declared in sttk.h) contains additional information about the error condition, usually the contents of errno(3) after a failed system call.
In the case of CHILD_KILLED, stCallCmdErrno contains the statßus of the child process as reported by wait(2).

BUGS
On systems where no usable vfork(2) is available, the value of stCallCmdErrno does not make sense in case of EXEC_FAILED.

Under IRIX stCallCmd sometimes (or always?) returns WAIT_ERROR where it should be EXEC_FAILED, NO_PROGRAM, or WRITE_FAILED.

AUTHORS
Jürgen Nickelsen <nickel@cs.tu-berlin.de> and Andreas.Lampen@cs.tu-berlin.de