Get command line parameter by name
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| Author: Chris Morgan (talk, contrib) |
Description
Please contact me if you have trouble with this function, cmorgan@alum.wpi.edu
A function that uses the GetParameters function to retrieve the value of a command line argument. I wanted an easy way to retrieve parameters and modified the example given in the NSIS documentation.
Usage
You can use this like:
Push "OUTPUT" ; push the search string onto the stack Push "DefaultValue" ; push a default value onto the stack Call GetParameterValue Pop $2 MessageBox MB_OK "Value of OUTPUT parameter is '$2'"
This retrieves VALUE from a command line of /OUTPUT=VALUE or "/OUTPUT=VALUE WITH SPACES"
Be sure to add the GetParameters function to your script otherwise the GetParameterValue function below will throw a compiler error. 216.162.36.2 13:01, 12 October 2005 (PDT) Harold Solomon, harold@seraphimpartners.com
The Function
; GetParameterValue ; Chris Morgan<cmorgan@alum.wpi.edu> 5/10/2004 ; -Updated 4/7/2005 to add support for retrieving a command line switch ; and additional documentation ; ; Searches the command line input, retrieved using GetParameters, for the ; value of an option given the option name. If no option is found the ; default value is placed on the top of the stack upon function return. ; ; This function can also be used to detect the existence of just a ; command line switch like /OUTPUT Pass the default and "OUTPUT" ; on the stack like normal. An empty return string "" will indicate ; that the switch was found, the default value indicates that ; neither a parameter or switch was found. ; ; Inputs - Top of stack is default if parameter isn't found, ; second in stack is parameter to search for, ex. "OUTPUT" ; Outputs - Top of the stack contains the value of this parameter ; So if the command line contained /OUTPUT=somedirectory, "somedirectory" ; will be on the top of the stack when this function returns ; ; Register usage ;$R0 - default return value if the parameter isn't found ;$R1 - input parameter, for example OUTPUT from the above example ;$R2 - the length of the search, this is the search parameter+2 ; as we have '/OUTPUT=' ;$R3 - the command line string ;$R4 - result from StrStr calls ;$R5 - search for ' ' or '"' Function GetParameterValue Exch $R0 ; get the top of the stack(default parameter) into R0 Exch ; exchange the top of the stack(default) with ; the second in the stack(parameter to search for) Exch $R1 ; get the top of the stack(search parameter) into $R1 ;Preserve on the stack the registers used in this function Push $R2 Push $R3 Push $R4 Push $R5 Strlen $R2 $R1+2 ; store the length of the search string into R2 Call GetParameters ; get the command line parameters Pop $R3 ; store the command line string in R3 # search for quoted search string StrCpy $R5 '"' ; later on we want to search for a open quote Push $R3 ; push the 'search in' string onto the stack Push '"/$R1=' ; push the 'search for' Call StrStr ; search for the quoted parameter value Pop $R4 StrCpy $R4 $R4 "" 1 ; skip over open quote character, "" means no maxlen StrCmp $R4 "" "" next ; if we didn't find an empty string go to next # search for non-quoted search string StrCpy $R5 ' ' ; later on we want to search for a space since we ; didn't start with an open quote '"' we shouldn't ; look for a close quote '"' Push $R3 ; push the command line back on the stack for searching Push '/$R1=' ; search for the non-quoted search string Call StrStr Pop $R4 ; $R4 now contains the parameter string starting at the search string, ; if it was found next: StrCmp $R4 "" check_for_switch ; if we didn't find anything then look for ; usage as a command line switch # copy the value after /$R1= by using StrCpy with an offset of $R2, # the length of '/OUTPUT=' StrCpy $R0 $R4 "" $R2 ; copy commandline text beyond parameter into $R0 # search for the next parameter so we can trim this extra text off Push $R0 Push $R5 ; search for either the first space ' ', or the first ; quote '"' ; if we found '"/output' then we want to find the ; ending ", as in '"/output=somevalue"' ; if we found '/output' then we want to find the first ; space after '/output=somevalue' Call StrStr ; search for the next parameter Pop $R4 StrCmp $R4 "" done ; if 'somevalue' is missing, we are done StrLen $R4 $R4 ; get the length of 'somevalue' so we can copy this ; text into our output buffer StrCpy $R0 $R0 -$R4 ; using the length of the string beyond the value, ; copy only the value into $R0 goto done ; if we are in the parameter retrieval path skip over ; the check for a command line switch ; See if the parameter was specified as a command line switch, like '/output' check_for_switch: Push $R3 ; push the command line back on the stack for searching Push '/$R1' ; search for the non-quoted search string Call StrStr Pop $R4 StrCmp $R4 "" done ; if we didn't find anything then use the default StrCpy $R0 "" ; otherwise copy in an empty string since we found the ; parameter, just didn't find a value done: Pop $R5 Pop $R4 Pop $R3 Pop $R2 Pop $R1 Exch $R0 ; put the value in $R0 at the top of the stack FunctionEnd
