en:docs:fapi:dosgetenv

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

en:docs:fapi:dosgetenv [2018/08/31 10:20] (current)
prokushev created
Line 1: Line 1:
 +
 +This call returns the address of the process environment string for the current process.
 +
 +==Syntax==
 + ​DosGetEnv (EnvSegment,​ CmdOffset)
 +
 +==Parameters==
 +;EnvSegment (PSEL) - output : Address of the selector for the environment segment.
 +;CmdOffset (PUSHORT) - output : Address of the offset to the command line within the environment segment.
 +
 +==Return Code==
 +;rc (USHORT) - return:​Return code descriptions are:
 +* 0  NO_ERROR
 +* 12 ERROR_INVALID_ACCESS ​
 +
 +==Remarks==
 +DosGetEnv can be used by dynamic link library routines that need to determine the environment for the current process.
 +
 +When a process issues [[DosExecPgm]] to start another process, the program that receives control is returned a pointer to the environment segment.
 +
 +==Bindings==
 +===C Binding===
 +<PRE>
 +#define INCL_DOSMISC
 +
 +USHORT ​ rc = DosGetEnv(EnvSegment,​ CmdOffset);
 +
 +PUSHORT EnvSegment; ​   /* Selector (returned) */
 +PUSHORT CmdOffset; ​    /* Command line offset (returned) */
 +
 +USHORT ​ rc;            /* return code */
 +</​PRE>​
 +
 +===MASM===
 +<PRE>
 +EXTRN  DosGetEnv:​FAR
 +INCL_DOSMISC ​     EQU 1
 +
 +PUSH@  WORD    EnvSegment ​  ;​Selector (returned)
 +PUSH@  WORD    CmdOffset ​   ;Command line offset (returned)
 +CALL   ​DosGetEnv
 +
 +Returns WORD
 +</​PRE>​
 +
 +==Example Code==
 +The following example shows how one may obtain information for program initialization. The program locates the environment segment and prints the name of the command from the command line. It then obtains the OS/2 version number and prints it. 
 +<PRE>
 +#define INCL_DOS
 +#include <​os2.h>​
 +#define ENVVARNAME "​PATH"​
 +
 +main()
 +{
 +  SEL       ​EnvSel; ​       /* Environment segment selector (returned) */
 +  USHORT ​   CmdOffset; ​    /* Offset into env. seg. of command line (returned) */
 +  PSZ FAR   ​*Commandline; ​ /* Pointer made by EnvSel and CmdOffset */
 +  USHORT ​   Version; ​      /* Version numbers (returned) */
 +  BYTE      MajorVer; ​     /* Major version number */
 +  BYTE      MinorVer; ​     /* Minor version number */
 +  USHORT ​   rc;            /* return code */
 +
 +  /** Locate environment segment and offset of command line. **/
 +  if(!(rc=DosGetEnv(&​EnvSel, ​      /* Env. seg. selector (returned) */
 +                    &​CmdOffset))) ​ /* Offset of command line (returned) */
 +    printf("​Environment located; selector is %x offset is %x\n", EnvSel,
 +            CmdOffset);
 +
 +  /** Use a macro to make a far pointer out of selector:​offset pair.  **/
 +  /** Notice the far-string pointer specification (%Fs) used to print **/
 +
 +  Commandline = MAKEP(EnvSel,​ CmdOffset);
 +  printf("​Command entered is %Fs.\n",​ Commandline);​
 +
 +  /** Obtain and print version info; use macros to extract info. **/
 +  /** We need to divide by 10 to obtain true version numbers. ​   **/
 +
 +  if(!(rc=DosGetVersion(&​Version)))
 +  {
 +    MajorVer = HIBYTE(Version) / 10;
 +    MinorVer = LOBYTE(Version) / 10;
 +    printf("​This is OS/2 version %d.%d\n",​ MajorVer, MinorVer);
 +  }
 +}
 +</​PRE>​
 +
 +
 +
 +====== Note ======
 +
 +Text based on [[http://​www.edm2.com/​index.php/​DosGetEnv]]
 +
 +{{page>​en:​templates:​fapi}}
 +
  

en/docs/fapi/dosgetenv.txt · Last modified: 2018/08/31 10:20 by prokushev