diff options
Diffstat (limited to 'doc/unload.n')
| -rw-r--r-- | doc/unload.n | 77 |
1 files changed, 51 insertions, 26 deletions
diff --git a/doc/unload.n b/doc/unload.n index 916c565..febd694 100644 --- a/doc/unload.n +++ b/doc/unload.n @@ -1,17 +1,15 @@ '\" -'\" Copyright (c) 2003 George Petasis, petasis@iit.demokritos.gr. +'\" Copyright (c) 2003 George Petasis <petasis@iit.demokritos.gr>. '\" '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" -'\" RCS: @(#) $Id: unload.n,v 1.3 2004/03/17 18:14:12 das Exp $ -'\" -.so man.macros .TH unload n 8.5 Tcl "Tcl Built-In Commands" +.so man.macros .BS '\" Note: do not modify the .SH NAME line immediately below! .SH NAME -unload \- Unload machine code. +unload \- Unload machine code .SH SYNOPSIS \fBunload \fR?\fIswitches\fR? \fIfileName\fR .br @@ -19,7 +17,6 @@ unload \- Unload machine code. .br \fBunload \fR?\fIswitches\fR? \fIfileName packageName interp\fR .BE - .SH DESCRIPTION .PP This command tries to unload shared libraries previously loaded @@ -27,28 +24,34 @@ with \fBload\fR from the application's address space. \fIfileName\fR is the name of the file containing the library file to be unload; it must be the same as the filename provided to \fBload\fR for loading the library. -\fIpackageName\fR is the name of the package, and is used to -compute the name of the unload procedure. -\fIinterp\fR is the path name of the interpreter from which to unload -the package (see the \fBinterp\fR manual entry for details); -if \fIinterp\fR is omitted, it defaults to the +The \fIpackageName\fR argument is the name of the package (as +determined by or passed to \fBload\fR), and is used to +compute the name of the unload procedure; if not supplied, it is +computed from \fIfileName\fR in the same manner as \fBload\fR. +The \fIinterp\fR argument is the path name of the interpreter from +which to unload the package (see the \fBinterp\fR manual entry for +details); if \fIinterp\fR is omitted, it defaults to the interpreter in which the \fBunload\fR command was invoked. -.LP +.PP If the initial arguments to \fBunload\fR start with \fB\-\fR then they are treated as switches. The following switches are currently supported: .TP \fB\-nocomplain\fR -Supresses all error messages. If this switch is given \fBunload\fR will +. +Suppresses all error messages. If this switch is given, \fBunload\fR will never report an error. .TP \fB\-keeplibrary\fR +. This switch will prevent \fBunload\fR from issuing the operating system call that will unload the library from the process. .TP \fB\-\|\-\fR +. Marks the end of switches. The argument following this one will be treated as a \fIfileName\fR even if it starts with a \fB\-\fR. +.SS "UNLOAD OPERATION" .PP When a file containing a shared library is loaded through the \fBload\fR command, Tcl associates two reference counts to the library @@ -57,7 +60,7 @@ loaded into normal (trusted) interpreters while the second describes how many times the library has been loaded into safe interpreters. As a file containing a shared library can be loaded only once by Tcl (with the first \fBload\fR call on the file), these counters track how many interpreters use the library. -Each subsequent call to \fBload\fR after the first, simply increaments the +Each subsequent call to \fBload\fR after the first simply increments the proper reference count. .PP \fBunload\fR works in the opposite direction. As a first step, \fBunload\fR @@ -78,15 +81,20 @@ instead of \fIpkg\fB_Unload\fR. If \fBunload\fR determines that a library is not unloadable (or unload functionality has been disabled during compilation), an error will be returned. If the library is unloadable, then \fBunload\fR will call the unload -procedure. If the unload procedure returns TCL_OK, \fBunload\fR will proceed +procedure. If the unload procedure returns \fBTCL_OK\fR, \fBunload\fR will proceed and decrease the proper reference count (depending on the target interpreter type). When both reference counts have reached 0, the library will be detached from the process. +.SS "UNLOAD HOOK PROTOTYPE" .PP The unload procedure must match the following prototype: +.PP .CS -typedef int Tcl_PackageUnloadProc(Tcl_Interp *\fIinterp\fR, int \fIflags\fR); +typedef int \fBTcl_PackageUnloadProc\fR( + Tcl_Interp *\fIinterp\fR, + int \fIflags\fR); .CE +.PP The \fIinterp\fR argument identifies the interpreter from which the library is to be unloaded. The unload procedure must return \fBTCL_OK\fR or \fBTCL_ERROR\fR to indicate whether or not it completed @@ -102,10 +110,11 @@ the library is used by other interpreters), library is used only by the target interpreter and the library will be detached from the application as soon as the unload procedure returns, the \fIflags\fR argument will be set to \fBTCL_UNLOAD_DETACH_FROM_PROCESS\fR. +.SS NOTES .PP The \fBunload\fR command cannot unload libraries that are statically linked with the application. -If \fIfileName\fR is an empty string, then \fIpackageName\fR must +If \fIfileName\fR is an empty string, then the \fIpackageName\fR argument must be specified. .PP If \fIpackageName\fR is omitted or specified as an empty string, @@ -114,21 +123,17 @@ This may be done differently on different platforms. The default guess, which is used on most UNIX platforms, is to take the last element of \fIfileName\fR, strip off the first three characters if they are \fBlib\fR, and use any following -.VS alphabetic and underline characters as the module name. -.VE For example, the command \fBunload libxyz4.2.so\fR uses the module name \fBxyz\fR and the command \fBunload bin/last.so {}\fR uses the module name \fBlast\fR. - .SH "PORTABILITY ISSUES" .TP \fBUnix\fR\0\0\0\0\0 . Not all unix operating systems support library unloading. Under such -an operating system \fBunload\fR returns an error (unless -nocomplain has -been specified). - +an operating system \fBunload\fR returns an error (unless \fB\-nocomplain\fR +has been specified). .SH BUGS .PP If the same file is \fBload\fRed by different \fIfileName\fRs, it will @@ -139,9 +144,29 @@ silently detached by the operating system (and as a result Tcl thinks the library is still loaded), it may be dangerous to use \fBunload\fR on such a library (as the library will be completely detached from the application while some interpreters will continue to use it). - +.SH EXAMPLE +.PP +If an unloadable module in the file \fBfoobar.dll\fR had been loaded +using the \fBload\fR command like this (on Windows): +.PP +.CS +load c:/some/dir/foobar.dll +.CE +.PP +then it would be unloaded like this: +.PP +.CS +\fBunload\fR c:/some/dir/foobar.dll +.CE +.PP +This allows a C code module to be installed temporarily into a +long-running Tcl program and then removed again (either because it is +no longer needed or because it is being updated with a new version) +without having to shut down the overall Tcl process. .SH "SEE ALSO" -info sharedlibextension, load, safe(n) - +info sharedlibextension, load(n), safe(n) .SH KEYWORDS binary code, unloading, safe interpreter, shared library +.\" Local Variables: +.\" mode: nroff +.\" End: |