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fpathconf, pathconf - get configuration values for files
#include <unistd.h> long fpathconf(int fd, int name); long pathconf(const char *path, int name);
fpathconf() gets a value for the configuration option name for the open file descriptor fd. pathconf() gets a value for configuration option name for the filename path. The corresponding macros defined in <unistd.h> are minimum values; if an application wants to take advantage of values which may change, a call to fpathconf() or pathconf() can be made, which may yield more liberal results. Setting name equal to one of the following constants returns the following configuration options: _PC_LINK_MAX returns the maximum number of links to the file. If fd or path refer to a directory, then the value applies to the whole directory. The corresponding macro is _POSIX_LINK_MAX. _PC_MAX_CANON returns the maximum length of a formatted input line, where fd or path must refer to a terminal. The corresponding macro is _POSIX_MAX_CANON. _PC_MAX_INPUT returns the maximum length of an input line, where fd or path must refer to a terminal. The corresponding macro is _POSIX_MAX_INPUT. _PC_NAME_MAX returns the maximum length of a filename in the directory path or fd that the process is allowed to create. The corresponding macro is _POSIX_NAME_MAX. _PC_PATH_MAX returns the maximum length of a relative pathname when path or fd is the current working directory. The corresponding macro is _POSIX_PATH_MAX. _PC_PIPE_BUF returns the size of the pipe buffer, where fd must refer to a pipe or FIFO and path must refer to a FIFO. The corresponding macro is _POSIX_PIPE_BUF. _PC_CHOWN_RESTRICTED returns nonzero if the chown(2) call may not be used on this file. If fd or path refer to a directory, then this applies to all files in that directory. The corresponding macro is _POSIX_CHOWN_RESTRICTED. _PC_NO_TRUNC returns nonzero if accessing filenames longer than _POSIX_NAME_MAX generates an error. The corresponding macro is _POSIX_NO_TRUNC. _PC_VDISABLE returns nonzero if special character processing can be disabled, where fd or path must refer to a terminal.
The limit is returned, if one exists. If the system does not have a limit for the requested resource, -1 is returned, and errno is unchanged. If there is an error, -1 is returned, and errno is set to reflect the nature of the error.
For an explanation of the terms used in this section, see attributes(7). ┌────────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├────────────────────────┼───────────────┼─────────┤ │fpathconf(), pathconf() │ Thread safety │ MT-Safe │ └────────────────────────┴───────────────┴─────────┘
Files with name lengths longer than the value returned for name equal to _PC_NAME_MAX may exist in the given directory. Some returned values may be huge; they are not suitable for allocating memory.
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