reading/printing a string with scanf in ARM assembler

Question

I'm playing around with some assembler on the RaspberryPi, calling functions from C library, printf and scanf. No problem with reading and printing characters, using %c, or decimals, using %d, but I'd like to see how one reads in a string of characters? For example, the following code:

.data                                                                            
 27 .balign 4                                                                        
 26 prompt:         .asciz  "What is your name? "                                    
 25 .balign 4                                                                        
 24 message:        .asciz  "Hello %s\n"                                             
 23 .balign 4                                                                        
 22 pattern:        .asciz  "%s"                                                     
 21 .balign 4                                                                        
 20 name:           .asciz  " "                                                      
 19 .balign 4                                                                        
 18 lr_bu:          .word   0                                                        
 17                                                                                  
 16 /* ------------------------------------------------------------ */               
 15 /* CODE Section                                                 */               
 14 /* ------------------------------------------------------------ */               
 13 .global main                                                                     
 12 .func main                                                                       
 11                                                                                  
 10 main:                                                                            
  9     @ Store the link register                                                    
  8     ldr     r1, =lr_bu                                                           
  7     str     lr, [r1]                                                             
  6                                                                                  
  5     @ display prompt                                                             
  4     ldr     r0, =prompt                                                          
  3     bl      printf                                                               
  2                                                                                  
  1     @ set up parameters for scanf to get input                                   
39      ldr     r0, =pattern                                                         
  1     ldr     r1, =name                                                            
  2     bl      scanf                                                                
  3                                                                                  
  4     @ print the message with name                                                
  5     ldr     r0, =message                                                         
  6     ldr     r1, =name                                                            
  7     ldr     r1, [r1]                                                             
  8     bl      printf                                                               
  9                                                                                  
 10     @ restore the link register                                                  
 11     ldr     lr, =lr_bu                                                           
 12     ldr     lr, [lr]                                                             
 13     bx      lr                                                                   
 14                                                                                  
 15 exit:                                                                            
 16     mov     r7, #1              @ exit gracefully
 17     swi     0

This produces a segmentation fault so obviously this is not the way to do it! Searched through dozens of articles and pages but all focus on decimal input and output rather than whole strings. Also written the C code and looked at the assembled listing but it wasn't a great deal of help ... to me.

Does it need to be read back out in a loop character by character?

I'd be grateful for any pointers to steer me in the right direction. I'm new to StackExchange so hopefully I've provided enough information and in the correct format but do advise if not.

Thanks

Answer 1

That fixed it, thanks Jester! I made the following changes:

name:   .asciz  "          "

and removed:

ldr  r1, [r1]

from the output section and magic happened! (well, I know it's not magic but ...)