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Pay attention to the environment variable "LD_IGNORE_MISSING_OBJECTS".

Browse Source 
If it is set to a nonempty string, then simply skip any missing
shared libraries.  This came up in a discussion long ago as a
potentially useful feature at sysinstall time.  For example, an
X11 utility could be used without the X libraries being present,
provided the utility had a mode in which no X functions were actually
called.
This commit is contained in:
John Polstra 1997-01-17 20:22:18 +00:00
parent c7e54a6a04
commit ac6c268b3d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=21819
6 changed files with 122 additions and 4 deletions
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26
gnu/usr.bin/ld/rtld/rtld.1
View File

@ -106,7 +106,7 @@ library-name, major-version-number, minor-version-number
recognises a number of environment variables that can be used to modify
its behaviour as follows:
.Pp
.Bl -tag -width "LD_TRACE_LOADED_OBJECTS_PROGNAME"
.Bl -tag -width "LD_IGNORE_MISSING_OBJECTS"
.It Ev LD_LIBRARY_PATH
A colon separated list of directories, overriding the default search path
for shared libraries.
@ -134,6 +134,30 @@ object. This is usually indicative of an incorrectly built library.
When set to a nonempty string, no warning messages of any kind are
issued. Normally, a warning is given if satisfactorily versioned
library could not be found.
.It Ev LD_IGNORE_MISSING_OBJECTS
When set to a nonempty string, makes it a nonfatal condition if
one or more required shared objects cannot be loaded.
Loading and execution proceeds using the objects that are
available.
A warning is produced for each missing object, unless the environment
variable
.Ev LD_SUPPRESS_WARNINGS
is set to a nonempty string.
.Pp
This is ignored for set-user-ID and set-group-ID programs.
.Pp
Missing shared objects can be ignored without errors if all the
following conditions hold:
.Bl -bullet
.It
They do not supply definitions for any required data symbols.
.It
No functions defined by them are called during program execution.
.It
The environment variable
.Ev LD_BIND_NOW
is unset or is set to the empty string.
.El
.It Ev LD_TRACE_LOADED_OBJECTS
When set to a nonempty string, causes
.Nm

11
gnu/usr.bin/ld/rtld/rtld.c
View File

@ -188,6 +188,7 @@ static int careful;
static int anon_fd = -1;
static char *ld_bind_now;
static char *ld_ignore_missing_objects;
static char *ld_library_path;
static char *ld_preload;
static char *ld_tracing;
@ -869,6 +870,15 @@ map_sods(parent)
* "not found" message.
*/
(void)alloc_link_map(NULL, sodp, parent, 0, 0);
} else if (ld_ignore_missing_objects) {
char *msg;
/*
* Call __dlerror() even it we're not going to use
* the message, in order to clear the saved message.
*/
msg = __dlerror(); /* Should never be NULL */
if (!ld_suppress_warnings)
warnx("warning: %s", msg);
} else /* Give up */
break;
@ -2022,6 +2032,7 @@ struct env_scan_tab {
} scan_tab[] = {
L("LD_LIBRARY_PATH=", 1, &ld_library_path)
L("LD_PRELOAD=", 1, &ld_preload)
L("LD_IGNORE_MISSING_OBJECTS=", 1, &ld_ignore_missing_objects)
L("LD_TRACE_LOADED_OBJECTS=", 0, &ld_tracing)
L("LD_BIND_NOW=", 0, &ld_bind_now)
L("LD_SUPPRESS_WARNINGS=", 0, &ld_suppress_warnings)

26
libexec/rtld-aout/rtld.1
View File

@ -106,7 +106,7 @@ library-name, major-version-number, minor-version-number
recognises a number of environment variables that can be used to modify
its behaviour as follows:
.Pp
.Bl -tag -width "LD_TRACE_LOADED_OBJECTS_PROGNAME"
.Bl -tag -width "LD_IGNORE_MISSING_OBJECTS"
.It Ev LD_LIBRARY_PATH
A colon separated list of directories, overriding the default search path
for shared libraries.
@ -134,6 +134,30 @@ object. This is usually indicative of an incorrectly built library.
When set to a nonempty string, no warning messages of any kind are
issued. Normally, a warning is given if satisfactorily versioned
library could not be found.
.It Ev LD_IGNORE_MISSING_OBJECTS
When set to a nonempty string, makes it a nonfatal condition if
one or more required shared objects cannot be loaded.
Loading and execution proceeds using the objects that are
available.
A warning is produced for each missing object, unless the environment
variable
.Ev LD_SUPPRESS_WARNINGS
is set to a nonempty string.
.Pp
This is ignored for set-user-ID and set-group-ID programs.
.Pp
Missing shared objects can be ignored without errors if all the
following conditions hold:
.Bl -bullet
.It
They do not supply definitions for any required data symbols.
.It
No functions defined by them are called during program execution.
.It
The environment variable
.Ev LD_BIND_NOW
is unset or is set to the empty string.
.El
.It Ev LD_TRACE_LOADED_OBJECTS
When set to a nonempty string, causes
.Nm

26
libexec/rtld-aout/rtld.1aout
View File

@ -106,7 +106,7 @@ library-name, major-version-number, minor-version-number
recognises a number of environment variables that can be used to modify
its behaviour as follows:
.Pp
.Bl -tag -width "LD_TRACE_LOADED_OBJECTS_PROGNAME"
.Bl -tag -width "LD_IGNORE_MISSING_OBJECTS"
.It Ev LD_LIBRARY_PATH
A colon separated list of directories, overriding the default search path
for shared libraries.
@ -134,6 +134,30 @@ object. This is usually indicative of an incorrectly built library.
When set to a nonempty string, no warning messages of any kind are
issued. Normally, a warning is given if satisfactorily versioned
library could not be found.
.It Ev LD_IGNORE_MISSING_OBJECTS
When set to a nonempty string, makes it a nonfatal condition if
one or more required shared objects cannot be loaded.
Loading and execution proceeds using the objects that are
available.
A warning is produced for each missing object, unless the environment
variable
.Ev LD_SUPPRESS_WARNINGS
is set to a nonempty string.
.Pp
This is ignored for set-user-ID and set-group-ID programs.
.Pp
Missing shared objects can be ignored without errors if all the
following conditions hold:
.Bl -bullet
.It
They do not supply definitions for any required data symbols.
.It
No functions defined by them are called during program execution.
.It
The environment variable
.Ev LD_BIND_NOW
is unset or is set to the empty string.
.El
.It Ev LD_TRACE_LOADED_OBJECTS
When set to a nonempty string, causes
.Nm

11
libexec/rtld-aout/rtld.c
View File

@ -188,6 +188,7 @@ static int careful;
static int anon_fd = -1;
static char *ld_bind_now;
static char *ld_ignore_missing_objects;
static char *ld_library_path;
static char *ld_preload;
static char *ld_tracing;
@ -869,6 +870,15 @@ map_sods(parent)
* "not found" message.
*/
(void)alloc_link_map(NULL, sodp, parent, 0, 0);
} else if (ld_ignore_missing_objects) {
char *msg;
/*
* Call __dlerror() even it we're not going to use
* the message, in order to clear the saved message.
*/
msg = __dlerror(); /* Should never be NULL */
if (!ld_suppress_warnings)
warnx("warning: %s", msg);
} else /* Give up */
break;
@ -2022,6 +2032,7 @@ struct env_scan_tab {
} scan_tab[] = {
L("LD_LIBRARY_PATH=", 1, &ld_library_path)
L("LD_PRELOAD=", 1, &ld_preload)
L("LD_IGNORE_MISSING_OBJECTS=", 1, &ld_ignore_missing_objects)
L("LD_TRACE_LOADED_OBJECTS=", 0, &ld_tracing)
L("LD_BIND_NOW=", 0, &ld_bind_now)
L("LD_SUPPRESS_WARNINGS=", 0, &ld_suppress_warnings)

26
libexec/rtld-elf/rtld.1
View File

@ -106,7 +106,7 @@ library-name, major-version-number, minor-version-number
recognises a number of environment variables that can be used to modify
its behaviour as follows:
.Pp
.Bl -tag -width "LD_TRACE_LOADED_OBJECTS_PROGNAME"
.Bl -tag -width "LD_IGNORE_MISSING_OBJECTS"
.It Ev LD_LIBRARY_PATH
A colon separated list of directories, overriding the default search path
for shared libraries.
@ -134,6 +134,30 @@ object. This is usually indicative of an incorrectly built library.
When set to a nonempty string, no warning messages of any kind are
issued. Normally, a warning is given if satisfactorily versioned
library could not be found.
.It Ev LD_IGNORE_MISSING_OBJECTS
When set to a nonempty string, makes it a nonfatal condition if
one or more required shared objects cannot be loaded.
Loading and execution proceeds using the objects that are
available.
A warning is produced for each missing object, unless the environment
variable
.Ev LD_SUPPRESS_WARNINGS
is set to a nonempty string.
.Pp
This is ignored for set-user-ID and set-group-ID programs.
.Pp
Missing shared objects can be ignored without errors if all the
following conditions hold:
.Bl -bullet
.It
They do not supply definitions for any required data symbols.
.It
No functions defined by them are called during program execution.
.It
The environment variable
.Ev LD_BIND_NOW
is unset or is set to the empty string.
.El
.It Ev LD_TRACE_LOADED_OBJECTS
When set to a nonempty string, causes
.Nm