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Diffstat (limited to 'man3/dladdr.3')
| -rw-r--r-- | man3/dladdr.3 | 275 |
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diff --git a/man3/dladdr.3 b/man3/dladdr.3 deleted file mode 100644 index 6929b01..0000000 --- a/man3/dladdr.3 +++ /dev/null @@ -1,275 +0,0 @@ -'\" t -.\" Copyright (C) 2015 Michael Kerrisk <mtk.manpages@gmail.com> -.\" and Copyright (C) 2008 Petr Baudis <pasky@suse.cz> (dladdr caveat) -.\" -.\" SPDX-License-Identifier: Linux-man-pages-copyleft -.\" -.TH dladdr 3 2023-10-31 "Linux man-pages 6.7" -.SH NAME -dladdr, dladdr1 \- translate address to symbolic information -.SH LIBRARY -Dynamic linking library -.RI ( libdl ", " \-ldl ) -.SH SYNOPSIS -.nf -.B #define _GNU_SOURCE -.B #include <dlfcn.h> -.P -.BI "int dladdr(const void *" addr ", Dl_info *" info ); -.BI "int dladdr1(const void *" addr ", Dl_info *" info ", void **" extra_info , -.BI " int " flags ); -.fi -.SH DESCRIPTION -The function -.BR dladdr () -determines whether the address specified in -.I addr -is located in one of the shared objects loaded by the calling application. -If it is, then -.BR dladdr () -returns information about the shared object and symbol that overlaps -.IR addr . -This information is returned in a -.I Dl_info -structure: -.P -.in +4n -.EX -typedef struct { - const char *dli_fname; /* Pathname of shared object that - contains address */ - void *dli_fbase; /* Base address at which shared - object is loaded */ - const char *dli_sname; /* Name of symbol whose definition - overlaps \fIaddr\fP */ - void *dli_saddr; /* Exact address of symbol named - in \fIdli_sname\fP */ -} Dl_info; -.EE -.in -.P -If no symbol matching -.I addr -could be found, then -.I dli_sname -and -.I dli_saddr -are set to NULL. -.P -The function -.BR dladdr1 () -is like -.BR dladdr (), -but returns additional information via the argument -.IR extra_info . -The information returned depends on the value specified in -.IR flags , -which can have one of the following values: -.TP -.B RTLD_DL_LINKMAP -Obtain a pointer to the link map for the matched file. -The -.I extra_info -argument points to a pointer to a -.I link_map -structure (i.e., -.IR "struct link_map\~**" ), -defined in -.I <link.h> -as: -.IP -.in +4n -.EX -struct link_map { - ElfW(Addr) l_addr; /* Difference between the - address in the ELF file and - the address in memory */ - char *l_name; /* Absolute pathname where - object was found */ - ElfW(Dyn) *l_ld; /* Dynamic section of the - shared object */ - struct link_map *l_next, *l_prev; - /* Chain of loaded objects */ -\& - /* Plus additional fields private to the - implementation */ -}; -.EE -.in -.TP -.B RTLD_DL_SYMENT -Obtain a pointer to the ELF symbol table entry of the matching symbol. -The -.I extra_info -argument is a pointer to a symbol pointer: -.IR "const ElfW(Sym) **" . -The -.IR ElfW () -macro definition turns its argument into the name of an ELF data -type suitable for the hardware architecture. -For example, on a 64-bit platform, -.I ElfW(Sym) -yields the data type name -.IR Elf64_Sym , -which is defined in -.I <elf.h> -as: -.IP -.in +4n -.EX -typedef struct { - Elf64_Word st_name; /* Symbol name */ - unsigned char st_info; /* Symbol type and binding */ - unsigned char st_other; /* Symbol visibility */ - Elf64_Section st_shndx; /* Section index */ - Elf64_Addr st_value; /* Symbol value */ - Elf64_Xword st_size; /* Symbol size */ -} Elf64_Sym; -.EE -.in -.IP -The -.I st_name -field is an index into the string table. -.IP -The -.I st_info -field encodes the symbol's type and binding. -The type can be extracted using the macro -.B ELF64_ST_TYPE(st_info) -(or -.B ELF32_ST_TYPE() -on 32-bit platforms), which yields one of the following values: -.in +4n -.TS -lb lb -lb l. -Value Description -STT_NOTYPE Symbol type is unspecified -STT_OBJECT Symbol is a data object -STT_FUNC Symbol is a code object -STT_SECTION Symbol associated with a section -STT_FILE Symbol's name is filename -STT_COMMON Symbol is a common data object -STT_TLS Symbol is thread-local data object -STT_GNU_IFUNC Symbol is indirect code object -.TE -.in -.IP -The symbol binding can be extracted from the -.I st_info -field using the macro -.B ELF64_ST_BIND(st_info) -(or -.B ELF32_ST_BIND() -on 32-bit platforms), which yields one of the following values: -.in +4n -.TS -lb lb -lb l. -Value Description -STB_LOCAL Local symbol -STB_GLOBAL Global symbol -STB_WEAK Weak symbol -STB_GNU_UNIQUE Unique symbol -.TE -.in -.IP -The -.I st_other -field contains the symbol's visibility, which can be extracted using the macro -.B ELF64_ST_VISIBILITY(st_info) -(or -.B ELF32_ST_VISIBILITY() -on 32-bit platforms), which yields one of the following values: -.in +4n -.TS -lb lb -lb l. -Value Description -STV_DEFAULT Default symbol visibility rules -STV_INTERNAL Processor-specific hidden class -STV_HIDDEN Symbol unavailable in other modules -STV_PROTECTED Not preemptible, not exported -.TE -.in -.SH RETURN VALUE -On success, these functions return a nonzero value. -If the address specified in -.I addr -could be matched to a shared object, -but not to a symbol in the shared object, then the -.I info\->dli_sname -and -.I info\->dli_saddr -fields are set to NULL. -.P -If the address specified in -.I addr -could not be matched to a shared object, then these functions return 0. -In this case, an error message is -.I not -.\" According to the FreeBSD man page, dladdr1() does signal an -.\" error via dlerror() for this case. -available via -.BR dlerror (3). -.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 dladdr (), -.BR dladdr1 () -T} Thread safety MT-Safe -.TE -.SH STANDARDS -GNU. -.SH HISTORY -.TP -.BR dladdr () -glibc 2.0. -.TP -.BR dladdr1 () -glibc 2.3.3. -.P -Solaris. -.SH BUGS -Sometimes, the function pointers you pass to -.BR dladdr () -may surprise you. -On some architectures (notably i386 and x86-64), -.I dli_fname -and -.I dli_fbase -may end up pointing back at the object from which you called -.BR dladdr (), -even if the function used as an argument should come from -a dynamically linked library. -.P -The problem is that the function pointer will still be resolved -at compile time, but merely point to the -.I plt -(Procedure Linkage Table) -section of the original object (which dispatches the call after -asking the dynamic linker to resolve the symbol). -To work around this, -you can try to compile the code to be position-independent: -then, the compiler cannot prepare the pointer -at compile time any more and -.BR gcc (1) -will generate code that just loads the final symbol address from the -.I got -(Global Offset Table) at run time before passing it to -.BR dladdr (). -.SH SEE ALSO -.BR dl_iterate_phdr (3), -.BR dlinfo (3), -.BR dlopen (3), -.BR dlsym (3), -.BR ld.so (8) |