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Diffstat (limited to 'doc/FileSystem.3')
| -rw-r--r-- | doc/FileSystem.3 | 30 |
1 files changed, 18 insertions, 12 deletions
diff --git a/doc/FileSystem.3 b/doc/FileSystem.3 index 0161dba..d4f4c25 100644 --- a/doc/FileSystem.3 +++ b/doc/FileSystem.3 @@ -4,7 +4,7 @@ '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" -'\" RCS: @(#) $Id: FileSystem.3,v 1.28 2002/07/08 10:14:24 vincentdarley Exp $ +'\" RCS: @(#) $Id: FileSystem.3,v 1.29 2002/07/08 12:08:34 vincentdarley Exp $ '\" .so man.macros .TH Filesystem 3 8.4 Tcl "Tcl Library Procedures" @@ -257,17 +257,23 @@ declared to be, allowing the same code to be used both on systems with and systems without support for files larger than 2GB in size. .PP The \fBTcl_FS...\fR are objectified and may cache internal -representations and other path-related strings (e.g. the current -working directory). One side-effect of this is that one must be -careful when passing in temporary objects with a refCount of zero. -Under some circumstances, the filesystem code may wish to retain a -reference to the passed in object, and so one must not assume that -after any of these calls return, the object still has a refCount of -zero - it may have been incremented. The practical lesson to learn -from this is that \fBTcl_Obj *path = Tcl_NewStringObj(...) ; -Tcl_FS...(path) ; Tcl_DecrRefCount(path)\fR is wrong, and may -segfault. The 'path' must have its refCount incremented before -passing it in, or decrementing it. +representations and other path-related strings (e.g. the current working +directory). One side-effect of this is that one must not pass in objects +with a refCount of zero to any of these functions. If such calls were +handled, they might result +in memory leaks (under some circumstances, the filesystem code may wish +to retain a reference to the passed in object, and so one must not assume +that after any of these calls return, the object still has a refCount of +zero - it may have been incremented), or in a direct segfault +due to the object being freed part way through the complex object +manipulation required to ensure that the path is fully normalized and +absolute for filesystem determination. The practical lesson to learn +from this is that \fBTcl_Obj *path = Tcl_NewStringObj(...) ; +Tcl_FS...(path) ; Tcl_DecrRefCount(path)\fR is wrong, and may segfault. +The 'path' must have its refCount incremented before passing it in, or +decrementing it. For this reason, objects with a refCount of zero are +considered not to be valid filesystem paths and calling any Tcl_FS API +with such an object will result in no action being taken. .PP \fBTcl_FSCopyFile\fR attempts to copy the file given by srcPathPtr to the path name given by destPathPtr. If the two paths given lie in the same |