nagios4/lib/runcmd.h

#ifndef NDO_LIBNAGIOS_RUNCMD_H_INCLUDED
#define NDO_LIBNAGIOS_RUNCMD_H_INCLUDED
#include <signal.h>

/**
 * @file runcmd.h
 * @brief runcmd library function declarations
 *
 * A simple interface to executing programs from other programs, using an
 * optimized and safer popen()-like implementation. It is considered safer in
 * that no shell needs to be spawned for simple commands, and the environment
 * passed to the execve()'d program is essentially empty.
 *
 * This code is based on popen.c, which in turn was taken from
 * "Advanced Programming in the UNIX Environment" by W. Richard Stevens.
 *
 * Care has been taken to make sure the functions are async-safe. The exception
 * is runcmd_init() which multithreaded applications or plugins must call in a
 * non-reentrant manner before calling any other runcmd function.
 *
 * @note This is inherited from the nagiosplugins project, although
 * it might need refactoring for performance later.
 * @{
 */

/** Return code bitflags for runcmd_cmd2strv() */
#define RUNCMD_HAS_REDIR (1 << 0) /**< I/O redirection */
#define RUNCMD_HAS_SUBCOMMAND  (1 << 1) /**< subcommands present */
#define RUNCMD_HAS_PAREN (1 << 2) /**< parentheses present in command */
#define RUNCMD_HAS_JOBCONTROL (1 << 3) /**< job control stuff present */
#define RUNCMD_HAS_UBSQ (1 << 4) /**< unbalanced single quotes */
#define RUNCMD_HAS_UBDQ (1 << 5) /**< unbalanced double quotes */
#define RUNCMD_HAS_WILDCARD (1 << 6) /**< wildcards present */
#define RUNCMD_HAS_SHVAR    (1 << 7) /**< shell variables present */


#define RUNCMD_EFD    (-1)  /**< Failed to pipe() or open() */
#define RUNCMD_EALLOC (-2)  /**< Failed to alloc */
#define RUNCMD_ECMD   (-3)  /**< Bad command */
#define RUNCMD_EFORK  (-4)  /**< Failed to fork() */
#define RUNCMD_EINVAL (-5)  /**< Invalid parameters */
#define RUNCMD_EWAIT  (-6)  /**< Failed to wait() */

/**
 * Initialize the runcmd library.
 *
 * Only multi-threaded programs that might launch the first external
 * program from multiple threads simultaneously need to bother with
 * this, and they must ensure this is called at least once in a non-reentrant
 * manner before calling any other runcmd function.
 */
extern void runcmd_init(void);

/**
 * Return pid of a command with a specific file descriptor
 * @param[in] fd stdout filedescriptor of the child to get pid from
 * @return pid of the child, or 0 on errors
 */
extern pid_t runcmd_pid(int fd);

/**
 * Return explanation of which system call or operation failed
 * @param code Error code returned by a library function
 * @return A non-free()'able string explaining where the error occurred
 */
extern const char *runcmd_strerror(int code);

/**
 * Start a command from a command string
 * @param[in] cmd The command to launch
 * @param[out] pfd Child's stdout filedescriptor
 * @param[out] pfderr Child's stderr filedescriptor
 * @param[in] env Currently ignored for portability
 * @param[in] iobreg The callback function to register the iobrokers for the read ends of the pipe
 * @param[in] iobregarg The "arg" value to pass to iobroker_register()
 */
extern int runcmd_open(const char *cmd, int *pfd, int *pfderr, char **env,
		void (*iobreg)(int, int, void *), void *iobregarg);

/**
 * Close a command and return its exit status
 * @note Don't use this. It's a retarded way to reap children suitable
 * only for launching a one-shot program.
 *
 * @param[in] fd The child's stdout filedescriptor
 * @return exit-status of the child, or -1 in case of errors
 */
extern int runcmd_close(int fd);

/**
 * Convert a string to a vector of arguments like a shell would
 * @note This might have bugs and is only tested to behave similar
 * to how /bin/sh does things. For csh or other non bash-ish shells
 * there are no guarantees.
 * @note The out_argv array has to be large enough to hold all strings
 * found in the command.
 * @param[in] str The string to convert to an argument vector
 * @param[out] out_argc The number of arguments found
 * @param[out] out_argv The argument vector
 * @return 0 on (great) success, or a bitmask of failure-codes
 * representing f.e. unclosed quotes, job control or output redirection.
 * See the RUNCMD_HAS_* and their ilk to find out about the flag.
 */
extern int runcmd_cmd2strv(const char *str, int *out_argc, char **out_argv);

/**
 * If you're using libnagios to execute a remote command, the 
 * static pid_t pids is not freed after runcmd_open
 * You can call this function when you're sure pids is no longer
 * in use, to keep down memory leaks
 */
extern void runcmd_free_pids(void);

/** @} */
/* INCLUDE_runcmd_h__ */
#endif