'\"! tbl | nroff \-man '\" t macro stdmacro .de SAMPLE .br .RS 0 .nf .nh .. .de ESAMPLE .hy .fi .RE .. .TH DEBUGINFOD_FIND_* 3 .SH NAME debuginfod_find_debuginfo \- request debuginfo from debuginfod .SH SYNOPSIS .nf .B #include .PP Link with \fB-ldebuginfod\fP. CONNECTION HANDLE .BI "debuginfod_client *debuginfod_begin(void);" .BI "void debuginfod_end(debuginfod_client *" client ");" LOOKUP FUNCTIONS .BI "int debuginfod_find_debuginfo(debuginfod_client *" client "," .BI " const unsigned char *" build_id "," .BI " int " build_id_len "," .BI " char ** " path ");" .BI "int debuginfod_find_executable(debuginfod_client *" client "," .BI " const unsigned char *" build_id "," .BI " int " build_id_len "," .BI " char ** " path ");" .BI "int debuginfod_find_source(debuginfod_client *" client "," .BI " const unsigned char *" build_id "," .BI " int " build_id_len "," .BI " const char *" filename "," .BI " char ** " path ");" .BI "int debuginfod_find_section(debuginfod_client *" client "," .BI " const unsigned char *" build_id "," .BI " int " build_id_len "," .BI " const char * " section "," .BI " char ** " path ");" OPTIONAL FUNCTIONS .BI "typedef int (*debuginfod_progressfn_t)(debuginfod_client *" client "," .BI " long a, long b);" .BI "void debuginfod_set_progressfn(debuginfod_client *" client "," .BI " debuginfod_progressfn_t " progressfn ");" .BI "void debuginfod_set_verbose_fd(debuginfod_client *" client "," .BI " int " fd ");" .BI "void debuginfod_set_user_data(debuginfod_client *" client "," .BI " void *" data ");" .BI "void* debuginfod_get_user_data(debuginfod_client *" client ");" .BI "const char* debuginfod_get_url(debuginfod_client *" client ");" .BI "int debuginfod_add_http_header(debuginfod_client *" client "," .BI " const char* " header ");" .BI "const char* debuginfod_get_headers(debuginfod_client *" client ");" .SH DESCRIPTION .BR debuginfod_begin () creates a \fBdebuginfod_client\fP connection handle that should be used with all other calls. .BR debuginfod_end () should be called on the \fBclient\fP handle to release all state and storage when done. .BR debuginfod_find_debuginfo (), .BR debuginfod_find_executable (), and .BR debuginfod_find_source () query the debuginfod server URLs contained in .BR $DEBUGINFOD_URLS (see below) for the debuginfo, executable or source file with the given \fIbuild_id\fP. \fIbuild_id\fP should be a pointer to either a null-terminated, lowercase hex string or a binary blob. If \fIbuild_id\fP is given as a hex string, \fIbuild_id_len\fP should be 0. Otherwise \fIbuild_id_len\fP should be the number of bytes in the binary blob. .BR debuginfod_find_source () also requires a \fIfilename\fP in order to specify a particular source file. \fIfilename\fP should be an absolute path that includes the compilation directory of the CU associated with the source file. 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: the caller may or may not elide \fB../\fP or \fB/./\fP or extraneous \fB///\fP 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 \fB//\fP to \fB/\fP in the path. .BR debuginfod_find_section () queries the debuginfod server URLs contained in .BR $DEBUGINFOD_URLS for the binary contents of an ELF/DWARF section contained in a debuginfo or executable file with the given \fIbuild_id\fP. \fIsection\fP should be the name of the desired ELF/DWARF section. If a server does not support section queries, debuginfod_find_section may query the server for the debuginfo and/or executable with \fIbuild_id\fP in order to retrieve and extract the section. If \fIpath\fP is not NULL and the query is successful, \fIpath\fP is set to the path of the file in the cache. The caller must \fBfree\fP() this value. The URLs in \fB$DEBUGINFOD_URLS\fP may be queried in parallel. As soon as a debuginfod server begins transferring the target file all of the connections to the other servers are closed. A \fBclient\fP handle should be used from only one thread at a time. A handle may be reused for a series of lookups, which can improve performance due to retention of connections and caches. .SH "RETURN VALUE" \fBdebuginfod_begin\fP returns the \fBdebuginfod_client\fP handle to use with all other calls. On error \fBNULL\fP will be returned and \fBerrno\fP will be set. If a find family function is successful, the resulting file is saved to the client cache and a file descriptor to that file is returned. The file descriptor points to the beginning of the file. The caller needs to \fBclose\fP() this descriptor. Otherwise, a negative error code is returned. .SH "OPTIONAL FUNCTIONS" A small number of optional functions are available to tune or query the operation of the debuginfod client. .SS "PROGRESS CALLBACK" As the \fBdebuginfod_find_*\fP() functions may block for seconds or longer, a progress callback function is called periodically, if configured with .BR debuginfod_set_progressfn (). This function sets a new progress callback function (or NULL) for the client handle. The given callback function is called from the context of each thread that is invoking any of the other lookup functions. It is given two numeric parameters that, if thought of as a numerator \fIa\fP and denominator \fIb\fP, together represent a completion fraction \fIa/b\fP. The denominator may be zero initially, until a quantity such as an exact download size becomes known. The progress callback function is also the supported way to \fIinterrupt\fP the download operation. (The library does \fInot\fP modify or trigger signals.) The progress callback must return 0 to continue the work, or any other value to stop work as soon as possible. Consequently, the \fBdebuginfod_find_*\fP() function will likely return with an error, but might still succeed. .SS "VERBOSE OUTPUT" The \fBdebuginfod_find_*\fP() functions may use several techniques to retrieve the requested files, through the cache or through one or multiple servers or file URLs. To show how a query is handled the .BR debuginfod_set_verbose_fd () can be used to set a particular file descriptor on which verbose output is given about the query steps and eventual errors encountered. .SS "USER DATA POINTER" A single \fIvoid *\fP pointer associated with the connection handle may be set any time via .BR \%debuginfod_set_user_data () , and retrieved via .BR \%debuginfod_get_user_data () . The value is undefined if unset. .SS "URL" The URL of the current or most recent outgoing download, if known, may be retrieved via .BR \%debuginfod_get_url () from the progressfn callback, or afterwards. It may be NULL. The resulting string is owned by the library, and must not be modified or freed. The caller should copy it if it is needed beyond the release of the client object. .SS "HTTP HEADER" Before each lookup function is initiated, a client application may add HTTP request headers. These are reset after each lookup function. .BR \%debuginfod_add_http_header () may be called with strings of the form .BR \%"Header:\~value" . These strings are copied by the library. A zero return value indicates success, but out-of-memory conditions may result in a non-zero \fI-ENOMEM\fP. If the string is in the wrong form \fI-EINVAL\fP will be returned. \fI$DEBUGINFOD_HEADERS_FILE\fP specifies a file to supply headers to outgoing requests. Each non-whitespace line of this file is handled as if .BR \%debuginfod_add_http_header () were called on the contents. Note that the current debuginfod-client library implementation uses libcurl, but you shouldn't rely on that fact. Don't use this function for replacing any standard headers, except for the User-Agent mentioned below. You can use this function to add authorization information for access control, or to provide optional headers to the server for logging purposes. By default, the library adds a descriptive \fIUser-Agent:\fP header to outgoing requests. If the client application adds a header with the same name, this default is suppressed. During or after a lookup, a client application may call .BR \%debuginfod_get_headers () to gather the subset of HTTP response headers received from the current or most recent debuginfod server. Only those headers prefixed with .BR X-DEBUGINFOD (case-insensitive) are kept. They are returned as a single string, with each "header: value" terminated with a \\n (not \\r\\n as in HTTP). It may be NULL. The resulting string is owned by the library, and must not be modified or freed. The caller should copy the returned string if it is needed beyond the release of the client object. .SH "MACROS" .SS "DEBUGINFOD_SONAME" Defined to the string that could be passed to .BR dlopen (3) if the library is loaded at runtime, for example .PP .in +4n .EX void *debuginfod_so = dlopen(DEBUGINFOD_SONAME, RTLD_LAZY); .EE .in .SH "SECURITY" .BR debuginfod_find_* () functions \fBdo not\fP include any particular security features. They trust 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. Passing user authentication information through the internal \fIlibcurl\fP library is not currently enabled, except for the basic plaintext \%\fIhttp[s]://userid:password@hostname/\fP style. (The debuginfod server does not perform authentication, but a front-end proxy server could.) .SH "ERRORS" The following list is not comprehensive. Error codes may also originate from calls to various C Library functions. .TP .BR EACCESS Denied access to resource located at the URL. .TP .BR ECONNREFUSED Unable to connect to remote host. Also returned when an HTTPS connection couldn't be verified (bad certificate). .TP .BR ECONNRESET Unable to either send or receive network data. .TP .BR EHOSTUNREACH Unable to resolve remote host. .TP .BR EINVAL One or more arguments are incorrectly formatted. \fIbuild_id\fP may be too long (greater than 256 characters), \fIfilename\fP may not be an absolute path or a debuginfod URL is malformed. .TP .BR EIO Unable to write data received from server to local file. .TP .BR EMLINK Too many HTTP redirects. .TP .BR ENETUNREACH Unable to initialize network connection. .TP .BR ENOENT Could not find the resource located at URL. Often this error code indicates that a debuginfod server was successfully contacted but the server could not find the target file. .TP .BR ENOMEM System is unable to allocate resources. .TP .BR ENOSYS \fB$DEBUGINFOD_URLS\fP is not defined. .TP .BR ETIME Query failed due to timeout. \fB$DEBUGINFOD_TIMEOUT\fP and \fB$DEBUGINFOD_MAXTIME\fP control this. .TP .BR EF2BIG Query aborted due to the file requested being too big. The \fB$DEBUGINFOD_MAXSIZE\fP controls this. .nr zZ 1 .so bookworm/libdebuginfod-common/debuginfod-client-config.7.en.gz .SH "SEE ALSO" .I "debuginfod(8)"