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Scribidi F y

In Episode 5, Gerald demonstrates file handling in WebAssembly by opening a file in read, write, and append modes sequentially. He successfully reads from, overwrites, and appends to a text file, verifying the output matches expectations. Gerald plans to implement persistent storage for future logging sessions.

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14 views2 pages

Scribidi F y

In Episode 5, Gerald demonstrates file handling in WebAssembly by opening a file in read, write, and append modes sequentially. He successfully reads from, overwrites, and appends to a text file, verifying the output matches expectations. Gerald plans to implement persistent storage for future logging sessions.

Uploaded by

horus.philostone
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as TXT, PDF, TXT or read online on Scribd
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Here it is.

---

Episode 5: The Three Modes


(Where WebAssembly reads, writes, and appends — in that order)

Tuesday morning. 8:59 AM. Gerald’s keyboard was already warm. He never left.

Today’s goal: open a file three times — once in "r" mode, once in "w" mode, and
once in "a" mode. He called it "full interaction."

He opened a new source file:


triple_access.c

He typed, slowly but with steady purpose:

#include <stdio.h>

int main() {
// Read existing content
FILE *fr = fopen("/sequence.txt", "r");
if (fr != NULL) {
char buffer[64];
while (fgets(buffer, sizeof(buffer), fr)) {
printf("%s", buffer);
}
fclose(fr);
}

// Overwrite the file


FILE *fw = fopen("/sequence.txt", "w");
if (fw == NULL) return 1;
fprintf(fw, "This file has been rewritten.\n");
fclose(fw);

// Append a line
FILE *fa = fopen("/sequence.txt", "a");
if (fa == NULL) return 2;
fprintf(fa, "Then appended by WebAssembly.\n");
fclose(fa);

return 0;
}

He compiled it, without ceremony.

emcc triple_access.c -o triple.html --preload-file sequence.txt

The console remained quiet during compilation. He appreciated that.

He loaded the HTML. The console displayed:

Initial placeholder line.

Then:

This file has been rewritten.


Then appended by WebAssembly.

It had overwritten the file, and then appended. He downloaded it. It matched
exactly.

He added to log.txt:

June 17, 9:22 AM


Tested sequential file modes: read → write → append.
Observed expected file mutation.
Output verified.

He tapped the keyboard lightly.

Then he created a flowchart in ASCII on paper:

[R] → [W] → [A]


↓ ↓ ↓
Read Overwrite Append

He labeled it: "The Life Cycle of a Text File."

At 9:35 AM, Gerald updated plan.txt:

Plan for Wednesday:


Mount IDBFS for persistent txt storage.
Simulate long-term logging session.

He leaned back. Outside, a bird landed on the windowsill. Gerald did not notice.

He was already thinking about persistence.

---

Next up: Episode 6: “The Memory That Lasted” — persistent file storage with
WebAssembly. Ready when you are.

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