explain_setpgid(3) Library Functions Manual explain_setpgid(3) NAME explain_setpgid - explain setpgid(2) errors SYNOPSIS #include <libexplain/setpgid.h> const char *explain_setpgid(pid_t pid, pid_t pgid); const char *explain_errno_setpgid(int errnum, pid_t pid, pid_t pgid); void explain_message_setpgid(char *message, int message_size, pid_t pid, pid_t pgid); void explain_message_errno_setpgid(char *message, int message_size, int er- rnum, pid_t pid, pid_t pgid); DESCRIPTION These functions may be used to obtain explanations for errors returned by the setpgid(2) system call. explain_setpgid const char *explain_setpgid(pid_t pid, pid_t pgid); The explain_setpgid function is used to obtain an explanation of an error returned by the setpgid(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail. The errno global variable will be used to obtain the error value to be de- coded. pid The original pid, exactly as passed to the setpgid(2) system call. pgid The original pgid, exactly as passed to the setpgid(2) system call. Returns: The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their ar- gument list. This will be overwritten by the next call to any lib- explain function which shares this buffer, including other threads. Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. Example: This function is intended to be used in a fashion similar to the following example: if (setpgid(pid, pgid) < 0) { fprintf(stderr, "%s\n", explain_setpgid(pid, pgid)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_setpgid_or_die(3) function. explain_errno_setpgid const char *explain_errno_setpgid(int errnum, pid_t pid, pid_t pgid); The explain_errno_setpgid function is used to obtain an explanation of an error returned by the setpgid(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much bet- ter, and indicate the underlying cause in more detail. errnum The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is neces- sary if you need to call any code between the system call to be ex- plained and this function, because many libc functions will alter the value of errno. pid The original pid, exactly as passed to the setpgid(2) system call. pgid The original pgid, exactly as passed to the setpgid(2) system call. Returns: The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their ar- gument list. This will be overwritten by the next call to any lib- explain function which shares this buffer, including other threads. Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. Example: This function is intended to be used in a fashion similar to the following example: if (setpgid(pid, pgid) < 0) { int err = errno; fprintf(stderr, "%s\n", explain_errno_setpgid(err, pid, pgid)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_setpgid_or_die(3) function. explain_message_setpgid void explain_message_setpgid(char *message, int message_size, pid_t pid, pid_t pgid); The explain_message_setpgid function is used to obtain an explanation of an error returned by the setpgid(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much bet- ter, and indicate the underlying cause in more detail. The errno global variable will be used to obtain the error value to be de- coded. message The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe. message_size The size in bytes of the location in which to store the returned message. pid The original pid, exactly as passed to the setpgid(2) system call. pgid The original pgid, exactly as passed to the setpgid(2) system call. Example: This function is intended to be used in a fashion similar to the following example: if (setpgid(pid, pgid) < 0) { char message[3000]; explain_message_setpgid(message, sizeof(message), pid, pgid); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_setpgid_or_die(3) function. explain_message_errno_setpgid void explain_message_errno_setpgid(char *message, int message_size, int er- rnum, pid_t pid, pid_t pgid); The explain_message_errno_setpgid function is used to obtain an explanation of an error returned by the setpgid(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail. message The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe. message_size The size in bytes of the location in which to store the returned message. errnum The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is neces- sary if you need to call any code between the system call to be ex- plained and this function, because many libc functions will alter the value of errno. pid The original pid, exactly as passed to the setpgid(2) system call. pgid The original pgid, exactly as passed to the setpgid(2) system call. Example: This function is intended to be used in a fashion similar to the following example: if (setpgid(pid, pgid) < 0) { int err = errno; char message[3000]; explain_message_errno_setpgid(message, sizeof(message), err, pid, pgid); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_setpgid_or_die(3) function. SEE ALSO setpgid(2) set process group explain_setpgid_or_die(3) set process group and report errors COPYRIGHT libexplain version 1.3 Copyright (C) 2011 Peter Miller explain_setpgid(3)
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT
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