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more clarity

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Remzi Arpaci-Dusseau
2022-09-19 10:12:41 -05:00
parent c363697dba
commit bbb5693c67
1 changed files with 7 additions and 2 deletions
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9
initial-xv6-tracer/README.md
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@@ -41,11 +41,16 @@ int getcount(void)
The first, `trace()`, simply records the pathname specified by the parameter `pathname`, into The first, `trace()`, simply records the pathname specified by the parameter `pathname`, into
some known location (e.g., an array of characters called `trace_pathname`). some known location (e.g., an array of characters called `trace_pathname`).
It should also reset the trace counter to 0, and enable tracing (i.e., set some kernel It should also reset the trace counter to 0, and enable tracing (i.e., set some kernel
internal integer, such as `trace_enabled`, to 1). internal integer, such as `trace_enabled`, to 1).
It should return 0 upon success, and -1 upon failure (e.g., if someone passes in a null pointer).
Note: assume for simplicity that the max pathname is 256 bytes. Also, it is ok to trace
a file that does not yet exist, so no need to check that.
The second, `getcount()`, returns the value of a counter (perhaps called `trace_counter` The second, `getcount()`, returns the value of a counter (perhaps called `trace_counter`
or something like that). This counter should be incremented every time any process calls the or something like that). This counter should be incremented every time any process calls the
`open()` system call if the pathname passed to open matches the pathname being traced. `open()` system call if the pathname passed to open matches the pathname being traced.
If tracing has not yet been enabled, it should simply return 0.
## Tips ## Tips