/ 
Tk804.025_beta1
/ pod/pTk/GetGC.pod
Security Advisories (6)
CVE-2006-4484 (2008-10-01)

Buffer overflow in the LWZReadByte_ function in the GD extension in allows remote attackers to have an unknown impact via a GIF file with input_code_size greater than MAX_LWZ_BITS, which triggers an overflow when initializing the table array.

CVE-2007-4769 (2008-01-09)

The regular expression parser in TCL before 8.4.17, as used in PostgreSQL 8.2 before 8.2.6, 8.1 before 8.1.11, 8.0 before 8.0.15, and 7.4 before 7.4.19, allows remote authenticated users to cause a denial of service (backend crash) via an out-of-bounds backref number.

CVE-2003-0107 (2003-03-07)

Buffer overflow in the gzprintf function in zlib 1.1.4, when zlib is compiled without vsnprintf or when long inputs are truncated using vsnprintf, allows attackers to cause a denial of service or possibly execute arbitrary code.

CVE-2007-4772 (2008-01-09)

The regular expression parser in TCL before 8.4.17, as used in PostgreSQL 8.2 before 8.2.6, 8.1 before 8.1.11, 8.0 before 8.0.15, and 7.4 before 7.4.19, allows context-dependent attackers to cause a denial of service (infinite loop) via a crafted regular expression.

CVE-2007-6067 (2008-01-09)

Algorithmic complexity vulnerability in the regular expression parser in TCL before 8.4.17, as used in PostgreSQL 8.2 before 8.2.6, 8.1 before 8.1.11, 8.0 before 8.0.15, and 7.4 before 7.4.19, allows remote authenticated users to cause a denial of service (memory consumption) via a crafted "complex" regular expression with doubly-nested states.

CVE-2017-12652 (2019-07-10)

libpng before 1.6.32 does not properly check the length of chunks against the user limit.

NAME

Tk_GetGC, Tk_FreeGC - maintain database of read-only graphics contexts

SYNOPSIS

#include <tk.h>

GC Tk_GetGC(tkwin, valueMask, valuePtr)

Tk_FreeGC(display, gc)

ARGUMENTS

Tk_Window tkwin (in)

Token for window in which the graphics context will be used.

"unsigned long" valueMask (in)

Mask of bits (such as GCForeground or GCStipple) indicating which fields of *valuePtr are valid.

XGCValues *valuePtr (in)

Pointer to structure describing the desired values for the graphics context.

Display *display (in)

Display for which gc was allocated.

GC gc (in)

X identifier for graphics context that is no longer needed. Must have been allocated by Tk_GetGC.

DESCRIPTION

Tk_GetGC and Tk_FreeGC manage a collection of graphics contexts being used by an application. The procedures allow graphics contexts to be shared, thereby avoiding the server overhead that would be incurred if a separate GC were created for each use. Tk_GetGC takes arguments describing the desired graphics context and returns an X identifier for a GC that fits the description. The graphics context that is returned will have default values in all of the fields not specified explicitly by valueMask and valuePtr.

Tk_GetGC maintains a database of all the graphics contexts it has created. Whenever possible, a call to Tk_GetGC will return an existing graphics context rather than creating a new one. This approach can substantially reduce server overhead, so Tk_GetGC should generally be used in preference to the Xlib procedure XCreateGC, which creates a new graphics context on each call.

Since the return values of Tk_GetGC are shared, callers should never modify the graphics contexts returned by Tk_GetGC. If a graphics context must be modified dynamically, then it should be created by calling XCreateGC instead of Tk_GetGC.

When a graphics context is no longer needed, Tk_FreeGC should be called to release it. There should be exactly one call to Tk_FreeGC for each call to Tk_GetGC. When a graphics context is no longer in use anywhere (i.e. it has been freed as many times as it has been gotten) Tk_FreeGC will release it to the X server and delete it from the database.

KEYWORDS

graphics context