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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-24 04:52:22 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-24 04:52:22 +0000 |
commit | 3d08cd331c1adcf0d917392f7e527b3f00511748 (patch) | |
tree | 312f0d1e1632f48862f044b8bb87e602dcffb5f9 /man/man3/readdir_r.3 | |
parent | Adding debian version 6.7-2. (diff) | |
download | manpages-3d08cd331c1adcf0d917392f7e527b3f00511748.tar.xz manpages-3d08cd331c1adcf0d917392f7e527b3f00511748.zip |
Merging upstream version 6.8.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'man/man3/readdir_r.3')
-rw-r--r-- | man/man3/readdir_r.3 | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/man/man3/readdir_r.3 b/man/man3/readdir_r.3 new file mode 100644 index 0000000..a46c19c --- /dev/null +++ b/man/man3/readdir_r.3 @@ -0,0 +1,145 @@ +'\" t +.\" Copyright (C) 2008, 2016 Michael Kerrisk <mtk.manpages@gmail.com> +.\" and Copyright (C) 2016 Florian Weimer <fweimer@redhat.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH readdir_r 3 2024-05-02 "Linux man-pages (unreleased)" +.SH NAME +readdir_r \- read a directory +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.B #include <dirent.h> +.P +.BI "[[deprecated]] int readdir_r(DIR *restrict " dirp , +.BI " struct dirent *restrict " entry , +.BI " struct dirent **restrict " result ); +.fi +.P +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.P +.BR readdir_r (): +.nf + _POSIX_C_SOURCE + || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE +.fi +.SH DESCRIPTION +This function is deprecated; use +.BR readdir (3) +instead. +.P +The +.BR readdir_r () +function was invented as a reentrant version of +.BR readdir (3). +It reads the next directory entry from the directory stream +.IR dirp , +and returns it in the caller-allocated buffer pointed to by +.IR entry . +For details of the +.I dirent +structure, see +.BR readdir (3). +.P +A pointer to the returned buffer is placed in +.IR *result ; +if the end of the directory stream was encountered, +then NULL is instead returned in +.IR *result . +.P +It is recommended that applications use +.BR readdir (3) +instead of +.BR readdir_r (). +Furthermore, since glibc 2.24, glibc deprecates +.BR readdir_r (). +The reasons are as follows: +.IP \[bu] 3 +On systems where +.B NAME_MAX +is undefined, calling +.BR readdir_r () +may be unsafe because the interface does not allow the caller to specify +the length of the buffer used for the returned directory entry. +.IP \[bu] +On some systems, +.BR readdir_r () +can't read directory entries with very long names. +When the glibc implementation encounters such a name, +.BR readdir_r () +fails with the error +.B ENAMETOOLONG +.IR "after the final directory entry has been read" . +On some other systems, +.BR readdir_r () +may return a success status, but the returned +.I d_name +field may not be null terminated or may be truncated. +.IP \[bu] +In the current POSIX.1 specification (POSIX.1-2008), +.BR readdir (3) +is not required to be thread-safe. +However, in modern implementations (including the glibc implementation), +concurrent calls to +.BR readdir (3) +that specify different directory streams are thread-safe. +Therefore, the use of +.BR readdir_r () +is generally unnecessary in multithreaded programs. +In cases where multiple threads must read from the same directory stream, +using +.BR readdir (3) +with external synchronization is still preferable to the use of +.BR readdir_r (), +for the reasons given in the points above. +.IP \[bu] +It is expected that a future version of POSIX.1 +.\" FIXME . +.\" http://www.austingroupbugs.net/view.php?id=696 +will make +.BR readdir_r () +obsolete, and require that +.BR readdir (3) +be thread-safe when concurrently employed on different directory streams. +.SH RETURN VALUE +The +.BR readdir_r () +function returns 0 on success. +On error, it returns a positive error number (listed under ERRORS). +If the end of the directory stream is reached, +.BR readdir_r () +returns 0, and returns NULL in +.IR *result . +.SH ERRORS +.TP +.B EBADF +Invalid directory stream descriptor \fIdirp\fP. +.TP +.B ENAMETOOLONG +A directory entry whose name was too long to be read was encountered. +.SH ATTRIBUTES +For an explanation of the terms used in this section, see +.BR attributes (7). +.TS +allbox; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR readdir_r () +T} Thread safety MT-Safe +.TE +.SH STANDARDS +POSIX.1-2008. +.SH HISTORY +POSIX.1-2001. +.SH SEE ALSO +.BR readdir (3) |