NAME¶

debuginfod-find - request debuginfo-related data

SYNOPSIS¶

debuginfod-find [OPTION]... debuginfo BUILDID
debuginfod-find [OPTION]... debuginfo PATH
debuginfod-find [OPTION]... executable BUILDID
debuginfod-find [OPTION]... executable PATH
debuginfod-find [OPTION]... source BUILDID /FILENAME
debuginfod-find [OPTION]... source PATH /FILENAME

DESCRIPTION¶

debuginfod-find queries one or more debuginfod servers for debuginfo-related data. In case of a match, it saves the the requested file into a local cache, prints the file name to standard output, and exits with a success status of 0. In case of any error, it exits with a failure status and an error message to standard error.

The debuginfod system uses buildids to identify debuginfo-related data. These are stored as binary notes in ELF/DWARF files, and are represented as lowercase hexadecimal. For example, for a program /bin/ls, look at the ELF note GNU_BUILD_ID:

% readelf -n /bin/ls | grep -A4 build.id
Note section [ 4] '.note.gnu.buildid' of 36 bytes at offset 0x340:
Owner          Data size  Type
GNU                   20  GNU_BUILD_ID
Build ID: 8713b9c3fb8a720137a4a08b325905c7aaf8429d

Then the hexadecimal BUILDID is simply:

8713b9c3fb8a720137a4a08b325905c7aaf8429d

In place of the hexadecimal BUILDID, debuginfod-find also accepts a path name to to an ELF binary, from which it extracts the buildid. In this case, ensure the file name has some character other than [0-9a-f]. Files ambiguously named files like "deadbeef" can be passed with a ./deadbeef extra path component.

debuginfo BUILDID¶

If the given buildid is known to a server, this request will result in a binary object that contains the customary .*debug_* sections. This may be a split debuginfo file as created by strip, or it may be an original unstripped executable.

executable BUILDID¶

If the given buildid is known to the server, this request will result in a binary object that contains the normal executable segments. This may be a executable stripped by strip, or it may be an original unstripped executable. ET_DYN shared libraries are considered to be a type of executable.

source BUILDID /SOURCE/FILE¶

If the given buildid is known to the server, this request will result in a binary object that contains the source file mentioned. The path should be absolute. Relative path names commonly appear in the DWARF file's source directory, but these paths are relative to individual compilation unit AT_comp_dir paths, and yet an executable is made up of multiple CUs. Therefore, to disambiguate, debuginfod expects source queries to prefix relative path names with the CU compilation-directory, followed by a mandatory "/".

Note: for software packaged by distributions, the CU compilation-directory may not be obvious. It can be found by inspecting AT_comp_dir values in downloaded debuginfo. For example, the comp_dir of the Fedora 37 version of /bin/ls can be found as follows:

% debuginfod-find debuginfo /bin/ls
~/.cache/debuginfod_client/03529d48345409576cd5c82a56ad08555088d353/
% eu-readelf -w ~/.cache/debuginfod_client/03529d48345409576cd5c82a56ad08555088d353/debuginfo | grep comp_dir


           comp_dir             (line_strp) "/usr/src/debug/coreutils-9.1-6.fc37.x86_64/separate"

Note: the caller may or may not elide ../ or /./ or extraneous /// sorts of path components in the directory names. debuginfod accepts both forms. Specifically, debuginfod canonicalizes path names according to RFC3986 section 5.2.4 (Remove Dot Segments), plus reducing any // to / in the path.

For example:

#include <stdio.h>	source BUILDID /usr/include/stdio.h
/path/to/foo.c	source BUILDID /path/to/foo.c
AT_comp_dir=/zoo/	source BUILDID /zoo//../bar/foo.c

OPTIONS¶

-v

Increase verbosity, including printing frequent download-progress messages and printing the http response headers from the server.

SECURITY¶

debuginfod-find does not include any particular security features. It trusts that the binaries returned by the debuginfod(s) are accurate. Therefore, the list of servers should include only trustworthy ones. If accessed across HTTP rather than HTTPS, the network should be trustworthy. Authentication information through the internal libcurl library is not currently enabled, except for the basic plaintext http[s]://userid:password@hostname/ style. (The debuginfod server does not perform authentication, but a front-end proxy server could.)

ENVIRONMENT VARIABLES¶

$TMPDIR: This environment variable points to a file system to be used for temporary files. The default is /tmp.
$DEBUGINFOD_URLS: This environment variable contains a list of URL prefixes for trusted debuginfod instances. Alternate URL prefixes are separated by space. This environment variable may be set by /etc/profile.d scripts reading /etc/debuginfod/*.urls files.
$DEBUGINFOD_CACHE_PATH: This environment variable governs the location of the cache where downloaded files and cache-control files are kept. The default directory is chosen based on other environment variables, see below.
$DEBUGINFOD_PROGRESS: This environment variable governs the default progress function. If set, and if a progressfn is not explicitly set, then the library will configure a default progressfn. This function will append a simple progress message periodically to stderr. The default is no progress function output.
$DEBUGINFOD_VERBOSE: This environment variable governs the default file descriptor for verbose output. If set, and if a verbose fd is not explicitly set, then the verbose output will be produced on STDERR_FILENO.
$DEBUGINFOD_RETRY_LIMIT: This environment variable governs the default limit of retry attempts. If a query failed with errno other than ENOENT, will initiate several attempts within the limit.
$DEBUGINFOD_TIMEOUT: This environment variable governs the download commencing timeout for each debuginfod HTTP connection. A server that fails to provide at least 100K of data within this many seconds is skipped. The default is 90 seconds. (Zero or negative means "no timeout".)
$DEBUGINFOD_MAXTIME: This environment variable dictates how long the client will wait to complete the download a file found on a server in seconds. It is best used to ensure that a file is downloaded quickly or be rejected. The default is 0 (infinite time).
$DEBUGINFOD_MAXSIZE: This environment variable dictates the maximum size of a file to download in bytes. This is best used if the user would like to ensure only small files are downloaded. A value of 0 causes no consideration for size, and the client may attempt to download a file of any size. The default is 0 (infinite size).
$DEBUGINFOD_HEADERS_FILE: This environment variable points to a file that supplies headers to outbound HTTP requests, one per line. The header lines shouldn't end with CRLF, unless that's the system newline convention. Whitespace-only lines are skipped.

CACHE¶

Before each query, the debuginfod client library checks for a need to clean the cache. If it's time to clean, the library traverses the cache directory and removes downloaded debuginfo-related artifacts and newly empty directories, if they have not been accessed recently.

Control files are located directly under the cache directory. They contain simple decimal numbers to set cache-related configuration parameters. If the files do not exist, the client library creates the files with the default parameter values as content.

After each query, the debuginfod client library deposits newly received files into a directory & file that is named based on the build-id. A failed query is also cached by a special file. The naming convention used for these artifacts is deliberately undocumented.

$XDG_CACHE_HOME/debuginfod_client/: Default cache directory, if $XDG_CACHE_HOME is set.
$HOME/.cache/debuginfod_client/: Default cache directory, if $XDG_CACHE_HOME is not set.
$HOME/.debuginfod_client_cache/: Deprecated cache directory, used only if preexisting.
cache_clean_interval_s: This control file gives the interval between cache cleaning rounds, in seconds. The default is 86400, one day. 0 means "immediately".
max_unused_age_s: This control file sets how long unaccessed debuginfo-related files are retained, in seconds. The default is 604800, one week. 0 means "immediately".
cache_miss_s: This control file sets how long to remember a query failure, in seconds. New queries for the same artifacts within this time window are short-circuited (returning an immediate failure instead of sending a new query to servers). This accelerates queries that probably would still fail. The default is 600, 10 minutes. 0 means "forget immediately".

Source file:	debuginfod-find.1.en.gz (from debuginfod 0.191-2)
Source last updated:	2024-07-13T04:30:43Z
Converted to HTML:	2024-10-22T15:09:53Z