diff options
| -rw-r--r-- | man3/dlopen.3 | 49 |
1 files changed, 27 insertions, 22 deletions
diff --git a/man3/dlopen.3 b/man3/dlopen.3 index b222a0d306..76a26cb97b 100644 --- a/man3/dlopen.3 +++ b/man3/dlopen.3 @@ -52,7 +52,7 @@ The four functions .BR dlclose (), .BR dlerror () implement the interface to the dynamic linking loader. -.SS "dlerror" +.SS "dlerror()" The function .BR dlerror () returns a human readable string describing the most recent error @@ -65,7 +65,7 @@ since the last call to .BR dlerror () . It returns NULL if no errors have occurred since initialization or since it was last called. -.SS "dlopen" +.SS "dlopen()" The function .BR dlopen () loads the dynamic library file named by the null-terminated @@ -83,7 +83,7 @@ Otherwise, the dynamic linker searches for the library as follows (see .BR ld.so (8) for further details): -.IP o +.IP o 4 (ELF only) If the executable file for the calling program contains a DT_RPATH tag, and does not contain a DT_RUNPATH tag, then the directories listed in the DT_RPATH tag are searched. @@ -220,7 +220,7 @@ has been called on it as many times as .BR dlopen () has succeeded on it. The -.B _init +.BR _init () routine, if present, is only called once. But a subsequent call with .B RTLD_NOW @@ -230,7 +230,7 @@ may force symbol resolution for a library earlier loaded with If .BR dlopen () fails for any reason, it returns NULL. -.SS "dlsym" +.SS "dlsym()" The function .BR dlsym () takes a "handle" of a dynamic library returned by @@ -271,7 +271,7 @@ will find the next occurrence of a function in the search order after the current library. This allows one to provide a wrapper around a function in another shared library. -.SS "dlclose" +.SS "dlclose()" The function .BR dlclose () decrements the reference count on the dynamic library handle @@ -282,22 +282,24 @@ symbols in it, then the dynamic library is unloaded. The function .BR dlclose () returns 0 on success, and non-zero on error. -.SS "The obsolete symbols _init and _fini" +.SS "The obsolete symbols _init() and _fini()" The linker recognizes special symbols .B _init and .BR _fini . If a dynamic library exports a routine named -.BR _init , +.BR _init (), then that code is executed after the loading, before .BR dlopen () returns. If the dynamic library exports a routine named -.BR _fini , +.BR _fini (), then that routine is called just before the library is unloaded. In case you need to avoid linking against the system startup files, -this can be done by giving gcc the "\-nostartfiles" parameter on -the command line. +this can be done by using the +.BR gcc (1) +.I \-nostartfiles" +command-line option. .LP Using these routines, or the gcc .B \-nostartfiles @@ -338,16 +340,19 @@ The function takes a function pointer and tries to resolve name and file where it is located. Information is stored in the -Dl_info structure: +.I Dl_info +structure: .sp +.in +0.25i .nf typedef struct { - const char *dli_fname;/* Filename of defining object */ - void *dli_fbase; /* Load address of that object */ - const char *dli_sname;/* Name of nearest lower symbol */ - void *dli_saddr; /* Exact value of nearest symbol */ + const char *dli_fname; /* Filename of defining object */ + void *dli_fbase; /* Load address of that object */ + const char *dli_sname; /* Name of nearest lower symbol */ + void *dli_saddr; /* Exact value of nearest symbol */ } Dl_info; .fi +.in .sp .BR dladdr () returns 0 on error, and non-zero on success. @@ -390,9 +395,7 @@ but not .BR dlvsym (). .SH EXAMPLE Load the math library, and print the cosine of 2.0: -.RS .nf -.if t .ft CW #include <stdio.h> #include <stdlib.h> @@ -424,9 +427,7 @@ main(int argc, char **argv) dlclose(handle); exit(EXIT_SUCCESS); } -.if t .ft P .fi -.RE .PP If this program were in a file named "foo.c", you would build the program with the following command: @@ -435,8 +436,12 @@ with the following command: gcc \-rdynamic \-o foo foo.c \-ldl .RE .PP -Libraries exporting _init() and _fini() will want to be compiled as -follows, using bar.c as the example name: +Libraries exporting +.BR _init () +and +.BR _fini () +will want to be compiled as +follows, using \fIbar.c\fP as the example name: .RS .LP gcc \-shared \-nostartfiles \-o bar bar.c |