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sd_device_enumerator_new(3) — Linux manual page

SD_DEVICE...RATOR_NEW(3) sd_device_enumerator_newSD_DEVICE...RATOR_NEW(3)

NAME        top

       sd_device_enumerator_new, sd_device_enumerator_ref,       sd_device_enumerator_unref, sd_device_enumerator_unrefp - Create,       reference, and release a device enumerator object

SYNOPSIS        top

#include <systemd/sd-device.h>int sd_device_enumerator_new(sd_device_enumerator **ret);sd_device_enumerator*sd_device_enumerator_ref(sd_device_enumerator *enumerator);sd_device_enumerator*sd_device_enumerator_unref(sd_device_enumerator *enumerator);voidsd_device_enumerator_unrefp(sd_device_enumerator **enumerator);

DESCRIPTION        top

       Thesd_device_enumeratorfamily of functions provides a way to       iterate over devices recognized bysystemd-udevd(8). The       enumerator allows filtering and matching devices by subsystem,       properties and other attributes.sd_device_enumerator_new()creates a new device enumerator object       and stores the result in the pointer referenced byret. Returns 0       on success, or a negative errno-style error code on failure.sd_device_enumerator_ref()increases the reference count of the       specifiedenumerator by one.sd_device_enumerator_unref()decreases the reference count of theenumerator by one. When the reference count reaches zero, the       enumerator object is destroyed and cannot be used anymore, so       further calls tosd_device_enumerator_unref()orsd_device_enumerator_unrefp()are illegal.sd_device_enumerator_unrefp()is similar tosd_device_enumerator_unref()but takes a pointer to a pointer to       ansd_device_enumeratorobject. This call is useful in conjunction       with GCC's and LLVM'sClean-up Variable Attribute[1]. Note that       this function is defined as an inline function. Use a declaration       like the following, in order to allocate asd_device_enumerator       object that is freed automatically as the code block is left:           {             __attribute__((cleanup(sd_device_enumerator_unrefp))) sd_device_enumerator *enumerator = NULL;             int r;             ...             r = sd_device_enumerator_new(&enumerator);             if (r < 0)               fprintf(stderr, "Failed to allocate sd_device_enumerator: %s\n", strerror(-r));             ...           }sd_device_enumerator_ref()andsd_device_enumerator_unref()       execute no operation if theenumerator isNULL.sd_device_enumerator_unrefp()will first dereference its argument,       which must not beNULL, and will execute no operation ifthat isNULL.

RETURN VALUE        top

sd_device_enumerator_new()returns 0 on success or a negative       errno-style error code on failure.sd_device_enumerator_ref()always returns the enumerator pointer.sd_device_enumerator_unref()always returnsNULL.Errors       Returned errors may indicate the following problems:-ENOMEM           Memory allocation failed.-EINVAL           The argument is invalid.

EXAMPLE        top

Example 1. Using sd_device_enumerator_new()           /* SPDX-License-Identifier: MIT-0 */           #include <stdio.h>           #include <systemd/sd-device.h>           int main(void) {               sd_device_enumerator *enumerator;               int r;               r = sd_device_enumerator_new(&enumerator);               if (r < 0) {                   fprintf(stderr, "Failed to create enumerator: %s\n", strerror(-r));                   return 1;               }               sd_device_enumerator_ref(enumerator);               sd_device_enumerator_unref(enumerator);               sd_device_enumerator_unref(enumerator);               return 0;           }

HISTORY        top

sd_device_enumerator_new(),sd_device_enumerator_ref(),sd_device_enumerator_unref(), andsd_device_enumerator_unrefp()       were added in version 240.

SEE ALSO        top

sd_device_ref(3),sd_device_enumerator_add_match_parent(3)

NOTES        top

        1. Clean-up Variable Attributehttps://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html

COLOPHON        top

       This page is part of thesystemd (systemd system and service       manager) project.  Information about the project can be found at       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have a       bug report for this manual page, see       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.       This page was obtained from the project's upstream Git repository       ⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11.  (At that       time, the date of the most recent commit that was found in the       repository was 2025-08-11.)  If you discover any rendering       problems in this HTML version of the page, or you believe there is       a better or more up-to-date source for the page, or you have       corrections or improvements to the information in this COLOPHON       (which isnot part of the original manual page), send a mail to       man-pages@man7.orgsystemd 258~rc2SD_DEVICE...RATOR_NEW(3)

Pages that refer to this page:sd_device_enumerator_add_match_parent(3), sd_device_enumerator_get_device_first(3), systemd.directives(7), systemd.index(7)

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